Topcon SRL-35 Operator's Manual
SRL-35
Operator’s Manual
Part Number 1003224-01
Rev. B
©Copyright September, 2013
All contents in this manual are copyrighted by Topcon. All rights reserved. The information contained herein
may not be used, accessed, copied, stored, displayed, sold, modified, published, distributed, or otherwise
reproduced without express written consent from Topcon.
• • • • •
Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v
Restrictions on Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Components and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SRL-35 Special Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Call Sign. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Temperature Protection of RF Power Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Protection of Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Radio Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
User Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
LED Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Display and Push Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SRL-35 LCD Display After Power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Display in Data Transfer Mode (transmit/receive mode) . . . . . . . . . . . . . . 8
Info - Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Display in Info Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Display in Setup Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
RF Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Priority RX/TX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Forward Error Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Error Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
User Data Whitening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Transparent Data Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Serial Interface, Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Handshake Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
CTS-line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
CD-line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
RTS-line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Radio Protocol Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Timing and Delays During Data Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Data Buffering in the Radio Data Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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Pause Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
TX Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Short Data Block Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Long Data Block Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Latency in PCC Transparent Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Transmission Delays using Pacific Crest 4FSK on 25 kHz channel . . . . . . . . . . . . . . 18
Transmission Delays using Pacific Crest GMSK on 25 kHz channel . . . . . . . . . . . . . 19
Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Programming Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Changing Parameters using TRU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Connecting in Modem Managing Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Configuring Radio in Modem Managing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Loading Frequencies/Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Changing Parameters using the LCD Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Changing Channel (Channel of the Active TX/RX Radio with Preset Frequencies) . . . . . . . . 27
Changing Protocol (Radio Protocol of the Active Radio) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Select Repeater (Set SRL-35 to Act as a Repeater) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Select FEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Saving Parameter Setup Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
TrimTalk, and Pacific Crest Mode Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Check List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Installation of a Radio Data Modem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
RS-232 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Antenna Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Mobile Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Base Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
General Antenna Installation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Factors Affecting the Quality and Distance of the Radio Connection . . . . . . . . . . . . . . . . . . . 36
Radio Field Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Repeater Mode and Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Repeater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Transmission: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Reception: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
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Connection Between Two Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
System of One Base Station and Several Substations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Using Repeaters and Addresses in the Same System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
System with Several Repeaters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Repeater Chain Using Address Pairs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Repeater Chain using Dual Addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Redundant Repeater Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Local/Remote Address Compatibility with PDL Modems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Data Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Power Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Antenna Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Warranty and Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Appendix B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Functional Delays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Transmission Related Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Transmission Delays When the Radio TX Frequency is Changed . . . . . . . . . . . . . . . . . . . . . . 54
Transmission Delays When Using a 12.5 kHz Radio Channel . . . . . . . . . . . . . . . . . . . . . . . . . 54
Transmission Delays without FEC-function (Forward Error Correction) . . . . . . . . . 54
Transmission Delays with FEC-function (Forward Error Correction) . . . . . . . . . . . 55
Transmission Delays using a 25 kHz Radio Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Transmission Delays without FEC Function (Forward Error Correction) . . . . . . . . . 56
Transmission Delays with FEC Function (Forward Error Correction) . . . . . . . . . . . 57
Appendix C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
Changing Parameters Using a Terminal Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Changing the Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Restoring Factory Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Changing Frequency (Active Radio Channel Frequency) . . . . . . . . . . . . . . . . . . . . . 61
Changing Reference Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Changing Channel Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Changing Radio Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Changing Addressing Settings (Primary And Secondary RX and TX Addresses) . . . 65
Changing Serial Port Settings (Port 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Modification of Handshaking Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Special Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Activating Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
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Restoring Factory Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Saving Modified Settings into the Permanent Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Changing Parameters Using the SL Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Radio Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Configuration of Radio Protocol using SL Commands . . . . . . . . . . . . . . . . 76
Other Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Regulatory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
Product Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
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• • • • • •
Preface
Thank you for purchasing this Topcon product. The materials available in this Manual (the “Manual”) have
been prepared by Topcon Positioning Systems, Inc. (“TPS”) for owners of Topcon products, and are designed
to assist owners with the use of the product and its use is subject to these terms and conditions (the “Terms
and Conditions”).
Please read the terms and conditions carefully.
Terms and Conditions
Use
This product is designed to be used by a professional. The user should have a good knowledge of the safe use
of the product and implement the types of safety procedures recommended by the local government
protection agency for both private use and commercial job sites.
Copyrights
All information contained in this Manual is the intellectual property of, and copyrighted material of TPS. All
rights are reserved. Do not use, access, copy, store, display, create derivative works of, sell, modify, publish,
distribute, or allow any third party access to, any graphics, content, information or data in this Manual
without TPS’ express written consent and may only use such information for the care and operation of the
product. The information and data in this Manual are a valuable asset of TPS and are developed by the
expenditure of considerable work, time and money, and are the result of original selection, coordination and
arrangement by TPS.
Trademarks
SRL-35™, TRU™, Topcon® and Topcon Positioning Systems™ are trademarks or registered trademarks of TPS.
Windows® is a registered trademark of Microsoft Corporation. The Bluetooth® word mark and logos are
owned by Bluetooth SIG, Inc. and any use of such marks by Topcon Positioning Systems, Inc. is used under
license. Other product and company names mentioned herein may be trademarks of their respective owners.
Disclaimer of Warranty
EXCEPT FOR ANY WARRANTIES IN AN APPENDIX OR A WARRANTY CARD ACCOMPANYING THE PRODUCT,
THIS MANUAL AND THE PRODUCT ARE PROVIDED “AS-IS.” THERE ARE NO OTHER WARRANTIES. TPS
DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR USE OR
PURPOSE. TPS AND ITS DISTRIBUTORS SHALL NOT BE LIABLE FOR TECHNICAL OR EDITORIAL ERRORS OR
OMISSIONS CONTAINED HEREIN; NOR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM
THE FURNISHING, PERFORMANCE OR USE OF THIS MATERIAL OR THE PRODUCT. SUCH DISCLAIMED
Preface
SRL-35 Operator’s Manual P/N: 1003224-01
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DAMAGES INCLUDE BUT ARE NOT LIMITED TO LOSS OF TIME, LOSS OR DESTRUCTION OF DATA, LOSS OF
PROFIT, SAVINGS OR REVENUE, OR LOSS OF THE PRODUCT’S USE. IN ADDITION TPS IS NOT RESPONSIBLE
OR LIABLE FOR DAMAGES OR COSTS INCURRED IN CONNECTION WITH OBTAINING SUBSTITUTE PRODUCTS
OR SOFTWARE, CLAIMS BY OTHERS, INCONVENIENCE, OR ANY OTHER COSTS. IN ANY EVENT, TPS SHALL
HAVE NO LIABILITY FOR DAMAGES OR OTHERWISE TO YOU OR ANY OTHER PERSON OR ENTITY IN EXCESS
OF THE PURCHASE PRICE FOR THE PRODUCT.
License Agreement
Use of any computer programs or software supplied by TPS or downloaded from a TPS website (the
“Software”) in connection with the product constitutes acceptance of these Terms and Conditions in this
Manual and an agreement to abide by these Terms and Conditions. The user is granted a personal, nonexclusive, non-transferable license to use such Software under the terms stated herein and in any case only
with a single product or single computer. You may not assign or transfer the Software or this license without
the express written consent of TPS. This license is effective until terminated. You may terminate the license
at any time by destroying the Software and Manual. TPS may terminate the license if you fail to comply
with any of the Terms or Conditions. You agree to destroy the Software and manual upon termination of
the use of the product. All ownership, copyright and other intellectual property rights in and to the
Software belong to TPS. If these license terms are not acceptable, return any unused software and manual.
Preface
Confidentiality
This Manual, its contents and the Software (collectively, the “Confidential Information”) are the
confidential and proprietary information of TPS. You agree to treat TPS’ Confidential Information with a
degree of care no less stringent that the degree of care you would use in safeguarding your own most
valuable trade secrets. Nothing in this paragraph shall restrict you from disclosing Confidential Information
to your employees as may be necessary or appropriate to operate or care for the product. Such employees
must also keep the Confidentiality Information confidential. In the event you become legally compelled to
disclose any of the Confidential Information, you shall give TPS immediate notice so that it may seek a
protective order or other appropriate remedy.
Website; Other Statements
No statement contained at the TPS website (or any other website) or in any other advertisements or TPS
literature or made by an employee or independent contractor of TPS modifies these Terms and Conditions
(including the Software license, warranty and limitation of liability).
Safety
Improper use of the product can lead to injury to persons or property and/or malfunction of the product.
The product should only be repaired by authorized TPS warranty service centers. Users should review and
heed the safety warnings in an Appendix.
Restrictions on Use
SRL-35
from one region and/or country to another. The user of a radio modem must take care that the said device
is not operated without the permission of the local authorities on frequencies other than those specifically
reserved and intended for use without a specific permit.
radio modems have been designed to operate on frequency ranges, the exact use of which differs
SRL-35 Operator’s Manual P/N: 1003224-01
vi
The allowed max output power depends on the type of station.
Preface
SRL-35
is allowed to be used in the following countries, either on license free channels or on channels
where the operation requires a license. More detailed information is available at the local frequency
management authority.
Countries: AT, AU, BE, BG, CA, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HU, IE, IS, IT, LT, LU, LV, MT, NL, NO,
PL, PT, RO, RU, SE, SK and US.
WARNING!
Users of SRL-35 radio modems in North America should be aware, that due to the allocation of
the frequency band 406.0 – 406.1 MHz for government use only, the use of radio modem on this frequency
band without a proper permit is strictly forbidden.
Miscellaneous
The above Terms and Conditions may be amended, modified, superseded, or canceled, at any time by TPS.
The above Terms and Conditions will be governed by, and construed in accordance with, the laws of the
State of California, without reference to conflict of laws.
Manual Conventions
This manual uses the following conventions:
Convention Description Example
Bold Menu, or drop-down menu selection FileExit (Click the File menu and click Exit)
Name of a dialog box or screen From the Connection screen...
Button or key commands Click Finish.
Mono User supplied text or variable Type guest, and click Enter.
Italic
Reference to another manual or help document Refer to the Topc o n Qu ic k Gu i de .
Further information to note about system configuration, maintenance, or setup.
Supplementary information that can have an adverse effect on system operation, system
performance, data integrity, measurements, or personal safety.
Notification that an action has the potential to result in system damage, loss of data, loss of
warranty, or personal injury.
SRL-35 Operator’s Manual P/N: 1003224-01
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Introduction
The SRL-35 is an IP67 classified UHF radio modem with a high power (35W) transmitter, wide 70 MHz tuning
range (403...473 MHz) in one hardware and selectable channel spacing. The SRL-35 can offer radio speeds up
to 19.2 kbps and has a selectable serial interface speed between 300 … 38 400 bps.
The SRL-35 includes a built-in LCD display, offering the user both new features and increased flexibility. No
longer do you have to rely on access to a PC or terminal device to check or alter the configuration of the unit,
now this can be achieved by viewing the LCD Display and using the four (4) push buttons. The display is also a
useful tool in testing the radio connection between radio modems.
The SRL-35 facilitates the construction of large radio networks using the built-in Message Routing function,
which is both fully transparent to the user and can be used with most system protocols.
The radio modem also offers option of error correction, utilizing the FEC method (Forward Error Correction).
FEC can be used to minimize errors caused by noisy channels.
Introduction
Figure 1: SRL-35
•
High output power of up to 35Watt
•
Wide 70 MHz (403-473 MHz) operating range
•
User selectable channel spacing (12.5, 20 or 25 kHz)
•
Fully compatible with third party radio broadcast
•
Multi-function user interface to indicate current operating status and configure the radio modem
1
Automatic prevention of overheating
•
Industry standard IP-67 rating to withstand harsh surveying and construction environment
1. 25W limited output power version is available as an order option for geographical areas where regulatory restriction on output power applies.
SRL-35 Operator’s Manual P/N: 1003224-01
1
Components and Accessories
Table 1. Radio Modem
Part Number Description Notes
1002759-01 SRL-35 Radio Modem External 35W Radio Modem
Table 2. Power Accessories
Part Number Description Notes
1002448-01 CABLE,POWER(4) w/SAE & battery leads Radio Power Cable
14-008025-01 ALLIGATOR CLIPS TO SAE CABLE SAE to Battery Cable
Table 3. Communication Cables
Introduction
Part Number Description Notes
1002447-01 Programming cable (1A) - D9f / ODU8m 2 m (no switch) Radio Interface (Data/Programming) Cable
1002451-01 Cable 2 m, ODU 8-pin male / 7-pin male Radio to Topcon Receivers (GR-5, HiPer V)
Interface Cable
Table 4. Antenna Accessories
Part Number Description Notes
1002782-01 NMO-TNC ANTENNA MOUNT Antenna Mount
1002452-01 Antenex antenna 406-430 MHz 406-430 MHz External Radio Antenna
1002453-01 Antenex antenna 430-450 MHz 430-450 MHz External Radio Antenna
1002454-01 Antenex antenna 450-470 MHz 450-470 MHz External Radio Antenna
14-008012-01LF CBL,TNC-TNC/RG58 (3 meter) TNC-TNC 3 meter Cable
14-008012-06LF CBL,TNC-TNC/RG58 (5 meter) TNC-TNC 5 meter Cable
Table 5. Carrying Case
Part Number Description Notes
20-830301-02 Soft case for Radio modem and cables Soft Carrying Case
Please contact your local Topcon dealer to determine the standard kit available in
your area and components included in the kit.
Components and Accessories
SRL-35 Operator’s Manual P/N: 1003224-01
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Default Settings
The SRL-35 is shipped with the following default settings (unless otherwise specifically agreed):
DEFAULT VALUES OF THE ADJUSTABLE SETTINGS (user can change settings later on)
Setting Default value Range
Radio frequency
Operating TX frequency 438.000 MHz Range: 403 - 473 MHz
Operating RX frequency 438.000 MHz Range: 403 - 473 MHz
Reference Frequency 438.000 MHz Range: 403 - 473 MHz
Channel Spacing 12.5 kHz Range: 12.5, 20 or 25 kHz
Radio settings
TX Power 35 W Range: 10, 20, 25 and 35 W
Signal threshold -115 dBm -80 … -118 dBm
FCS OFF ON/OFF
Introduction
Table 6. Default Settings
TX-Start Delay 0 ms 0-65535 ms
Radio Compatibility SATEL 3AS SATELLINE-3AS, PCC 4-FSK, PCC GMSK, TrimTalk 450s
(P), TrimTalk450s (T), PCC-FST
Addressing
RX Address OFF ON/OFF
TX Address OFF ON/OFF
RX addressing to RS port OFF ON/OFF
TX address auto switch OFF ON/OFF
Serial port 1
Status ON ON/OFF
Interface RS-232 Fixed
Data speed 9600 bps 300, 600, 1200, 2400, 4800, 9600, 19200, 38400 bps
Data bits 8 7, 8, 9
Parity bits None None, Even, Odd
Stop bits 1 1, 2
Handshaking Handshaking lines apply to the DATA-port.
Default Settings
CTS Clear to send Clear to send, TX buffer state
CD RSSI threshold RSSI- threshold, Data on channel,
Always ON, External Antenna Control
RTS Ignored Ignored, Flow Control, Reception Control
Pause length 3 bytes 3 … 255 bytes
Additional setup
Error correction OFF ON/OFF
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Table 6. Default Settings
Error check OFF ON/OFF
Repeater OFF ON/OFF
SL-commands ON ON/OFF
Priority TX RX/TX
FullCR16 Check OFF ON/OFF
Routing OFF ON/OFF
Te st s OFF ON/OFF
The power cable (+Vb and GND) must be connected to a power supply with a proper output voltage
(+9…+16
V
) and with a minimum output current of 15A.
DC
Basic settings for the serial port of the host computer, when using a terminal program (TRU) to
communicate with the SRL-35 radio modem, are as follows: “COM1, 9600 bps, 8-bit data, none parity, 1
stop bit”.
If the serial port designated as COM1 in the host computer is reserved, any other free serial port in the host
computer can be used (with the settings listed).
Introduction
Terms “PCC”, “PacCrest”, and “PDL” are used interchangeably in this document as well as in
common industry practice.
SRL-35 Special Features
Call Sign
The SRL-35 has a CALL SIGN identifier feature required in some countries. A call sign can be formally
assigned by a government agency, informally adopted by individuals or organizations, or even
cryptographically encoded to disguise identity of a station.
A call sign is an FCC (in US) or other regulatory authority assigned identifier that is issued along with the
license for operating a radio modem. This field is for entering your call sign. The modem automatically
broadcasts the specified call sign periodically. If this field is empty, there is no call sign information.
Call sign can be transmitted using Topcon Receiver Utility (TRU). Advanced call sign setup can be found in
Program menu clause Radio settings and further in its sub clause Call sign. Refer to the Settings chapter for
detail on TRU and Program menu. Call sign has three (3) different setups. With Call Sign Mode you can set
Morse code transmission ON or OFF. Call Sign ID defines which Morse code will be transmitted. Only capital
letters and numbers are allowed. If the digits are wrong kind, there will be message: Value error. Small
letters will be converted to capital letters automatically. If Call Sign ID field remains empty, the Call Sign
transmission will not be activated. Call Sign Timer is the transmission delay of Morse codes. Minimum and
default transmission time is 15 minutes.
During Call sign transmission the CTS-line of the modem is not in active state. This is to inform terminal
equipment that the modem is not ready to neither receive data from serial port nor forward it. The modem
deletes all data (also SL commands), which has arrived to serial port during call sign transmission. Call sign
transmission lasts 1-4 seconds depending on the number of digits.
SRL-35 Special Features
SRL-35 Operator’s Manual P/N: 1003224-01
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Temperature Protection of RF Power Amplifier
RF power amplifier is protected against overheating. The power of transmitter is lowered step by step if the
inner temperature exceeds certain levels as shown below.
Table 7. Temperature
Temperature inside a modem Carrier power
Over 75°C 25 W
80°C 20 W
85°C 10 W
90°C 0 W (transmitter OFF)
When the ambient temperature is under 30°C and transmitter duty cycle does not exceed 40%, the
temperature inside the modem does not exceed the trigger level.
The internal temperature is measured in the beginning of every transmission and at once when modem
cools down. The carrier power increases with falling temperature so that at 88°C carrier power goes to
10W, at 83°C to 20W, at 78°C to 25W and at 73°C the modem operates again at the full 35W carrier power.
Introduction
Protection of Current
In case of a bad antenna impedance matching the current consumption of the Power Amplifier may be too
high. For this reason the maximum current is limited to 12 A. If the current tends to increase over 12 A, the
automatic power control decreases the power level until the current drops under 11.5 A. LCD indicates the
actual power level of the transmitter. A new transmission starts always with the nominal power level. The
power control scheme is applied only when the nominal power level is 35W.
SRL-35 Special Features
SRL-35 Operator’s Manual P/N: 1003224-01
5
Radio Interface
User Interface
Power Connector
Communication Interface
RF Connector
(Not Shown in Photo)
The SRL-35 radio has three interfaces; Communication, User, and RF, and the Power connection. The power
connector on SRL-35 is a 4-pin mini style ODU connector. This chapter describes three interfaces available on
the SRL-35 in detail.
Figure 2: Radio Interfaces
Serial Interface
The radio modem is referred to as DCE (Data Communication Equipment) whereas the PC is referred to as DTE
(Data Terminal Equipment). The SRL-35 includes a 8-pin ODU which contains all the connections required to
establish communication between the radio modem, acting as the DCE, and the PC, acting as the DTE.
All EMC requirements set forth by authorities have been taken into account in the design of the radio modem.
The radio modem user is thereby not required to take any special actions regarding EMC-shielding (of the radio
modem).
The radio modem has one serial port,
Table 8. 8-pin ODU Pinouts
Signal 8-pin ODU
RX 4
TX 5
CTS 2
RTS 1
GND 3
MODE 6
Port 1
which complies with the RS-232 standard.
Description of Pins:
Radio Interface
•
RX = Output of the data received from the radio modem to the DTE.
•
TX = Input of the data to be transmitted from the DTE to the radio modem.
•
CTS = C
lear To Send.
SRL-35 Operator’s Manual P/N: 1003224-01
6
•
RTS = R
•
MODE =
equest To Send.
operational mode. When the MODE-line is connected to ground (GND), the radio modem
enters the Programming Mode, which is used to change the settings of the radio modem (i.e.
configuration, set-up). If the MODE-line is not connected, the radio modem will enter the Data
Transfer Mode, in which data can be transmitted and received. The Programming Mode is used only
when installing a radio modem and changing the operational parameters of a network. Normally the
radio modem is always in the Data Transfer Mode.
•
GND = both the negative pole of the operating voltage and the signal ground.
User Interface
LED Indicators
There are five (5) LED indicators on the front panel of the radio modem, and they give an indication of the
status of the serial port and the radio interface.
LED Indication OFF Red Orange Green
RTS RTS-line status Inactive Active
Radio Interface
Table 9. Description of the LED-indicators
CTS CTS-line status Inactive Active
TX TX-line status No data Data Test TX a c tive
RX RX-line status No data Data
CD Radio status No signal Transmission Noise Reception
Display and Push Buttons
The SRL-35 includes a LCD Display with a backlight. In the Data Transfer Mode the display will show the
operating settings of the radio modem, for example the radio field strength and the supply voltage. By
using the push buttons and the LCD Display, it is possible to change most of the settings of the radio
modem, without the need for an external terminal. The display backlight illuminates automatically as soon
as a button is pressed.
The radio modem will shift into the Programming Mode by pressing the
the menu shows a listing of the changeable parameters.
With the help of the main menu, sub-menus can be selected which in turn can be used to change the
settings. You can always return to the previous higher level of the menu structure by pressing the
(or BACK) push buon (●). Pressing the 5 or 6 buon changes sengs or moves in the menu. Selecons
are confirmed by pressing the
selected by pressing the
SELECT
NEXT
button (see following page).
or
SET
button. In case of numerical values the digit to be changed is
SETUP
button (■). When activated
CANCEL
User Interface
SRL-35 LCD Display After Power-up
The display shows the basic information which is revolving automatically in 5 seconds.
SRL-35 Operator’s Manual P/N: 1003224-01
7
Display in Data Transfer Mode (transmit/receive mode)
Radio Interface
n-123 11.5V
CH4 10W
462.37500/12.5
INFO SETUP
Info - Setup
By pressing the
By pressing the
INFO
buon (●) the modem goes to detailed informaon about the modem’s sengs.
SETUP
button (■) the modem goes to the programming menu.
Display in Info Mode
Pressing
Protocol
PacCrest - 4FSK
Exit
shows the next window.
n-123: Field strength of last received transmission
or noise level.
11.5V = Supply Voltage/Battery level indicator.
CH4 = Current Channel
10W = Current Output Transmission Power
462.37500 = Operational TX/RX Frequency
12.5 = Channel Spacing
Protocol
Repeater OFF
FEC OFF
Port 1 9600/8N1
Exit
RX Address
RX1 OFF
RX2 OFF
Exit
TX Address
TX1 OFF
TX2 OFF
Exit
Repeater
FEC
Port 1 : Port interface and status
RX Address
TX Address
User Interface
SRL-35 Operator’s Manual P/N: 1003224-01
8
Radio Interface
S/N XXXXXX
FW XXXXXX
Exit
Board: SPL0005E
+SLR-35
IM:05
Exit
Display in Setup Mode
Serial Number
FW: Firmware Version
Board: HW version
IM: Interface module type
RF Interface
The SRL-35 has a single TNC type RF-connector with impedance of 50 Ohm.
When the modem is supplied the frequency is set to “default channel”. The user can change the frequency
afterwards by 70 MHz. Of course, all local regulations set forth by the authorities must be taken into
consideration.
The data speed of the radio interface is set to “default speed”. It can also be set afterwards.
RF Interface
SRL-35 Operator’s Manual P/N: 1003224-01
9
A channel spacing of 25 kHz enables a data speed of 19200 bps and a channel spacing of 12.5 / 20 kHz
enables, correspondingly, a data speed of 9600 bps. The data speed of the radio interface is always fixed
(19200 bps or 9600 bps) irrespective of the data speed of the serial interface. If the data speeds of the radio
interface and the serial interface differ from each other, the radio modem will buffer the data in transfer
temporarily, so no data loss will occur.
Transmitter
The output power of the transmitter is adjustable. The greatest allowable power depends on limits set by
local authorities, which should not be exceeded under any circumstances. The output power of the
transmitter should be set to the smallest possible level, which still ensures error free connections under
variable conditions. Large output power levels using short connection distances can, in the worst case,
cause disturbances to the overall operation of the system.
Table 10. Typical output power levels
OUTPUT POWER dBm
10 W +40
20 W +43
Radio Interface
25 W +44
35 W +45,4
A product variant providing 25 W power levels is available by separate order.
Setting the radio data modem output power level to that which exceeds the regulations
set forth by local authorities is strictly forbidden. The setting and/or using of nonapproved power levels may lead to prosecution. Topcon and its distributors are not
responsible for any illegal use of its radio equipment, and are not responsible in any way
of any claims or penalties arising from the operation of its radio equipment in ways
contradictory to local regulations and/or requirements and/or laws.
Receiver
The sensitivity of the receiver depends on the channel spacing of the radio modem (=data speed of the
radio interface) and on the mode of the FEC (error correction) according to the table below:
RF Interface
Table 11. Receiver Channel Spacing and FEC
Channel
spacing
25 kHz -108 dBm -111 dBm
20 kHz -111 dBm -114 dBm
12.5 kHz -111 dBm -114 dBm
FEC OFF FEC ON
SRL-35 Operator’s Manual P/N: 1003224-01
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The Signal Threshold Level setting of the receiver determines a level, above which the search for the actual
data transfer signal is active. It is recommended that values given in the table are used. If the Signal
Threshold Level setting is set too low (the CD-LED is ON constantly), it is possible that the receiver is trying
to synchronize itself with noise, in which case, the actual data transmission might remain unnoticed.
Alternatively, weak data transmissions will be rejected, even though they would be otherwise acceptable.
Priority RX/TX
The SRL-35 offers a Priority setting, which selects the priority between reception and transmission. The
setting can be changed in Programming Mode. By default, transmission has higher priority than reception
i.e. the default value is Priority TX.
Priority TX means that a terminal device attached to a radio modem decides the timing of the transmission.
The transmitter is immediately switched on when the terminal device starts to output data. Should
reception be in progress, the radio modem will stop it and change to a transmit state. There is no need to
use any handshaking for the control of timing.
Priority RX means that a radio modem tries to receive all data currently in the air. If a terminal outputs data
to be transmitted (or an SL command) it will buffered. The radio modem will wait until the reception has
stopped before transmitting the buffered data. This will result in timing slacks to the system, but decreases
the number of collisions on the air; this is particularly useful in systems based on multiple random accesses.
Radio Interface
To t ogg le the Priority setting in the programming menu, select:
1) Priority RX / TX
If the Repeater Function has been set on, priority setting is automatically switched to RX mode.
Forward Error Correction
F
orward Error Correction, FEC-function is switched ON (or OFF) by using the Programming Mode. When
activated, the FEC-function will cause the SRL-35 to automatically add additional error correction
information, which increases the amount of transmitted data by 30%. It is used by the receiving radio
modem to correct erroneous bits - as long as the ratio of correct and erroneous bits is reasonable.
Error correction improves the reliability of data transfer via the radio interface especially in unfavorable
conditions. FEC-function should be used when link distances are long and/or if there are many disturbances
in the radio channels used. The use of the FEC-function will, however decrease the data transfer
throughput of data by about 30%. The list of exact delays when using FEC-function, are introduced in
appendix B.
To switch the FEC-function ON in the Programming Mode, select:
1) Error correction ON
RF Interface
Error Checking
When the error checking is switched on, the radio modem will add a checksum to the transmitted data.
When the data is received, the checksums are verified before data is forwarded to the serial port. There are
two different options for error checking that can be accessed in the Additional Setup menu in Programming
Mode:
SRL-35 Operator’s Manual P/N: 1003224-01
11
2) Error check
6) Full CRC16 check
Error check checks data partially while data is received.
Full CRC16 check function adds two checksum characters at the end of the user data message. At the
reception end the receiver receives first the whole package and if the checksum matches the data message
is forwarded to the serial port. If Full CRC16 check is selected it must be set ON for all radio modems in the
same network. Otherwise the checksum characters appear at the end of user message on the serial port.
User Data Whitening
In some cases, if the user data includes a large number of constant characters, additional bit errors may
appear. The use of error correction (FEC) is recommended in such cases. If that is not possible, the Data
whitening feature can be used to improve the reliability of data transfer. The feature is set on/off in the
programming mode.
Radio Interface
RF Interface
SRL-35 Operator’s Manual P/N: 1003224-01
12
Transparent Data Transmission
Serial Interface, Data Format
The SRL-35 serial interface uses an asynchronous data format. No external synchronizing signal is needed, since
necessary timing information is acquired from the start and stop bits transmitted before and after each data
field bits (byte).
The data transfer speed of the serial interfaces can be set to 300, 600, 1200, 2400, 4800, 9600, 19200 or 38400
bps (bits per second). The length of the data field must be 7, 8 or 9 bits. When using a data field length of 7 or
8 bits, a parity bit may also be used.
Example:
corresponds to a binary value of ”11001100”) and with a start bit value of ”0”, parity bit set to either “NO”
(NONE), ”0” or ”1” and with a stop bit value of ”1”, the possible combinations are listed in the table below:
If the settings of data speed, character length, parity or the number of stop bits differ between the radio
modem and the terminal, errors will be introduced into the transferred data. The serial port settings of each
individual radio modem in a system can all be different apart from the data length setting (7, 8 or 9 bits), which
must always be the same in each individual radio data modem. In other words, the serial port used, the data
transfer speed, parity and number of stop bits; can be different in different parts of a same system. The serial
port settings can be changed in the Programming Mode.
Serial interface settings of the modem and terminal device connected to it must match.
With an 8-bit data character length and taking, for example, a decimal value of ”204”, (which
Handshake Lines
When using the RS-232 serial interface, handshake signals can be used to control data transfer. Handshake
signals are used, for example, by the radio modem to inform the terminal that the radio channel is busy, and
that it cannot initiate transmission. The terminal can also control the radio modem via RTS-line.
Table 12. Handshake Lines
Line Direction
CTS To term i n a l
RTS To mo d e m
CD To term i n a l
A common way of using handshaking signals is to monitor the CTS-line and ignore the others. Usually the
terminal is fast enough to handle the data received by the radio modem, so the use of RTS-line is not necessary.
Handshaking is not needed if the system protocol is designed to prevent collisions (data contention) by the use
of polling, or if there is little traffic and also if there is no harm from occasional data contention situations
(several radio modems try to transmit at the same time).
Transparent Data Transmission
SRL-35 Operator’s Manual P/N: 1003224-01
13
CTS-line
The options for CTS-line are:
Transparent Data Transmission
1) Clear To Send
CTS will shift into inactive state during data reception and transmission.
2) TX buffer state
overflowing. This typically happens when the serial interface data transfer speed is greater than
the radio interface transfer speed and the size of transmitted messages is large.
CTS is active when the radio modem is ready to accept data for new transmission.
CTS will shift into inactive state only if the radio modem’s TX buffer is in danger of
CD-line
The CD handshaking options are not supported by the SRL-35 modem.
The options for CD-line are:
1) RSSI-threshold
reception exists on the radio channel. It doesn’t make any difference if the signal is an actual
data transmission, a signal of a radio transmitter not belonging to the system, or even an
interference signal caused for example, by a computer or a peripheral device. CD is also active
when the radio modem in question is transmitting.
2) Data on channel
CD will not react to interference signals.
CD is active whenever a signal with a level exceeding the level required for
CD will switch to active state only after recognition of a valid data transmission.
3) Always ON
which use the CD-line as an indicator of an active connection (the radio modem can transmit and
receive at any time).
4) External Antenna Control
CD is always in the active state. This option can be used with terminal equipment,
RTS-line
The options for RTS-line are:
1) Ignored
2) Flow control
Non-active state of the RTS-line will force the radio modem to buffer the received data. This option is used
if the terminal device is too slow to handle data received from the radio modem.
3) Reception control
enables reception (as normal). Non-active RTS-line will interrupt reception process immediately, even if
the radio modem is receiving a data packet. This option is used to force the radio modem into WAIT State
for an immediate channel change. Radio Protocol Support
RTS-line status is ignored.
The radio modem transmits data to the terminal device only when the RTS-line is active.
RTS-line controls the reception process of the radio modem. An active RTS-line
Serial Interface, Data Format
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Radio Protocol Support
The SRL-35 radio modem supports the following radio protocols for data transfer.
•
Satelline-3AS
•
PCC 4-FSK
•
PCC GMSK
•
TrimTalk450s(P)
•
TrimTalk450s(T)
•
PCC-FST
Transparent Data Transmission
Table 13. Radio Protocols
Protocol Modulation
Satelline-3AS 4-FSK 9600 19200
PCC 4-FSK 4-FSK 9600 19200
PCC GMSK GMSK 4800 9600
TrimTalk450s(P) GMSK 4800 9600
TrimTalk450s(T) GMSK 4800 9600
PCC-FST GMSK 9600 19200
a. Use of PDL and Satel protocols is recommended in applications where possible.
Compatibility with TrimTalk is subject to some restrictions.
a
Link rate
(@ 12.5 kHz)
Link rate
(@ 25 kHz)
The SRL-35 radio modem supports additional to the original SATEL 3AS data transfer also:
•
Pacific Crest compatible data transfer over the air, if the opponent Pacific Crest modems operate in
the transparent mode/FEC ON/Scrambling ON that is the most common setup among RTK
applications. The other modes are currently not supported.
•
TRIMTALK® 450s compatible data transfer over the air.
The SRL-35 radio modem provides the following radio compatibility settings:
•
•
•
•
•
So far, only the transparent mode is implemented, since it is the most commonly used and recommended
by the user manuals. The ARQ based protocols with ACK/NACK schemes are not preferred in RTK applications that apply one-way communication.
Radio Protocol Support
Pacific Crest 4-FSK modulation, Transparent mode/FEC ON/Scrambling ON.
Pacific Crest GMSK modulation, Transparent mode/FEC ON/Scrambling ON.
TRIMTALK GMSK modulation, Transparent mode
TrimTalk450s(T) = TrimTalk450s GMSK (RX fitted to Trimble transmitter)
Pacific Crest-FST = Pacific Crest Transparent FST (4-FSK), FEC ON/Scrambling ON.
Refer to “Settings” on page 20 for setting the radio protocol.
SRL-35 Operator’s Manual P/N: 1003224-01
15
Timing and Delays During Data Transmission
When using a radio modem for data transmission, certain delays will be formed through the use of a radio
interface and from the radio modem circuitry itself. These delays exist when the radio modem switches
from Standby Mode to Data Transfer Mode and during reception and transmission of data. For detailed
delay values in each case see Appendix B.
Data Buffering in the Radio Data Modem
Whenever the radio modem is in Data Transfer Mode it monitors both the radio channel and the serial
interface. When the terminal device starts data transmission the radio modem switches to transmission
mode. At the beginning of each transmission a synchronization signal is transmitted and this signal is
detected by another radio modem, which then switches into receive mode. During the transmission of the
synchronization signal the radio modem buffers data into its memory. Transmission ends when a pause is
detected in the data sent by the terminal device, and after all buffered data has been transmitted. When
the serial interface speed is the same or slower than the speed of the radio interface, the internal transmit
buffer memory cannot overflow. However, when the serial interface speed exceeds the speed of the radio
interface, data will eventually fill transmit buffer memory. In this instance, it will take a moment after the
terminal device has stopped transmission of data for the radio modem to empty the buffer and before the
transmitter switches off. The maximum size of transmit buffer memory is one kilobyte (1 kB). If the terminal
device does not follow the status of the CTS-line and transmits too much data to the radio modem, the
buffer will be emptied and the transmission is restarted.
Transparent Data Transmission
In the receive mode, the buffer works principally in the above described way thus evening out differences
in data transfer speeds. If the terminal device transmits data to a radio modem in receive mode, the data
will go into transmit buffer memory. If the modem is set to TX priority mode the transmission starts
immediately as soon as data packet arrives to serial interface TD line.
Pause Length
The modem recognizes a pause on the serial line (a pause is defined as a time with no status changes on
the RS-232 interface TX-line). The pause detection is used as criteria for:
•
End of radio transmission - When the transmit buffer is empty and a pause is detected, the modem
stops the transmission and will then change the radio to the receive mode.
•
SL-command recognition - For a SL-command to be valid, a pause must be detected before the
actual “SL…” character string.
•
User address recognition - In order for the start character to be detected, a pause must precede it in
transmission.
Traditionally, in asynchronous data communication, pauses have been used to separate serial messages
from each other. However, the use of non-real-time operating systems (frequently used on PC-type
hardware) often adds random pauses, which may result in the user data splitting into two or more separate
RF transmissions. This may cause problems especially in the systems including repeater stations.
Radio Protocol Support
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In order to match the operation of the radio modem to the user data, the Pause length parameter can be
adjusted on the programming menu. It may have any value between 3 and 255 characters. The default
value is 3 characters.
•
The absolute time of Pause length is depending on the serial port settings. For example, 1
character is ~1.04 ms at 9600 bps / 8N1 (10 bits).
•
The maximum absolute time is always 170 ms independent from the value of the Pause
length given in the set-up.
•
An increase in the Pause length increases the round trip delay of the radio link
correspondingly; this is due to the fact that the radio channel is occupied for the time of the
Pause length after each transmission (the time it takes to detect a pause). If this is not
acceptable, the TX delay setting may also be useful in special cases.
TX Delay
The radio modem can be configured to delay the beginning of a radio transmission by 1...65000ms. This
function can be used to prevent packet contention in a system, where all substations would otherwise
answer a poll of a base-station simultaneously. During this delay data sent to the radio modem is buffered.
Although the priority setting is RX, radio modem is prevented to change over to receiving mode during the
period of the TX delay. If this function is not needed, the delay time should be set to 0 ms.
Transparent Data Transmission
Testing
The radio modem can be switched to the Test M ode, where it will send a test packet on the radio channel.
The test packet is a normal data transmission, which can be used, for example, when directing antennas
during system installation.
When the test packet transmission has been switched on and saved by using the Programming Mode, the
transmitting radio modem needs only a power supply and an antenna.
If the channel spacing of the radio modems is 25 kHz, it is recommended to use 38400 bps as a serial data
speed of the receiving radio modem. In the case of 12.5 / 20 kHz channel spacing the data speed of 19200
bps is recommended.
Refer to “Changing Parameters Using a Terminal Device” on page 58 to enable test mode
"ON" (Option 9) using a terminal program.
There are two Tes t Mod es :
Short Data Block Test
In this test mode the radio modem sends a short test string, which is preceded by a consecutive number,
and it ends to the line feed character. The short data block is repeated continuously after 1 second break.
Short data block test is suitable for running data communication tests. Error-free reception of data can be
monitored using a suitable terminal program (TRU).
Radio Protocol Support
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