Motorola 92FT4848, 92FT3802, 92FT4849 User Manual

PRELIMINARY USERS MANUAL

Model Chart for the Vehicular Repeater System Model 750

Model Number				Description
P2080A				ASTRO Spectra Compatible VRS Model 750 (136-174 MHz)
	P2081A			ASTRO Spectra Compatible VRS Model 750 (403-470 MHz)
		P2082A		ASTRO Spectra Compatible VRS Model 750 (450-512 MHz)
			Item Number	Description
X	X	X	HHN4044A	VRS 750 Housing
X	X	X	HLN6855A	VRS 750 Mounting Assembly
X	X	X	PLN7780A	VRS 750 Controller Board
X	X	X	HLN6856A	XCVR Hardware
X			PUD1001A	VHF Transceiver
	X		PUE1036A	UHF R1 Transceiver
		X	PUE1037A	UHF R2 Transceiver
Note 1	Note 1	Note 1	HKN6153A	Cable, Mobile-to-VRS
Note 2	Note 2	Note 2	HKN6154A	Cable, Siren-to-VRS
Note 3	Note 3	Note 3	6881094C84	VRS 750 Detailed Service Manual
X	X	X	6881087C79	Safety Pamphlet
X	X	X	2884606M01	Mini-UHF crimp connector
X	X	X	3305873U04	Chassis Label
X	X	X		Front Label
X	X	X		XCVR Label
X	X	X		Packing Kit
			3085031D02	Cable, VRS Programming (optional)
			NTN4056A	Adapter, VRS Flash programming (optional)
			NKN6460A	y-cable kit for dual controlhead w/vrs (optional)
			TLN5277B	DC filter for excessive alternator whine (optional)
				Global Tuning Tool - CD ROM (optional)
Note 1	With option xxxxA
Note 2	With option xxxxB
Note 3	One item per 10 units

VRS750 SPECIFICATIONSVHF

GENERAL	TRANSMITTER	RECEIVER
Model: P2080A (136 – 174 MHz)	RF Power Out:	Intermodulation per EIA:
	275 mW to 2 W tunable	70 dB
Number of Channels: 1, T1=R1
Frequency:	Spurious and Harmonic	Hum and Noise:
Programmable, Synthesized	Emissions:
Frequency Channel
Channel Spacing:	-36 dBm < 1 GHz	-40dBm @ 25 kHz
	-30 dBm > 1 GHz	-35dBm @ 12.5 kHz
12.5/20/25 kHz
	Frequency Stability:	Reference Sensitivity(typical):
Operation Temp. Range:	±2.5 ppm @ 25 kHz	0.28µV (-118dBm) at 12 dB
	±2.5 ppm @ 12.5 kHz	SINAD
-30°C to +60°C
Primary Power:	Modulation Limiting(max):	Conducted Spurious Rejection:
13.8 VDC ± 20%, Negative Ground	±2.5 kHz @ 12.5 kHz	70 dB
	±4.0 kHz @ 20 kHz
	±5.0 kHz @ 25 kHz
DC Current Drain(max):	Audio Response: (from	Adjacent Channel Selectivity:
	6dB/octave pre-emphasis, 300
	to 3000 Hz)
120mA Receive	+1, -3 dB	60 dB @ 12.5 kHz
500mA Transmit @ 275mW		70 dB @ 25/30 kHz
1.10A Transmit @2W	Audio Distortion:
	3% Typical @ 1 kHz, 60%	Audio Response (0.3 – 3 kHz):
	maximum deviation
Squelch Operation:Private-Line		+1 to –3 dB
required for repeater access
	FM Hum and Noise: -40dB
Duty Cycle: Intermittent per EIA at		Audio Distortion
275mW		3% Typical @ Mobile Rated
		Audio*
	TX Attack Time: 32 ms
	Typical
PPI Sample time: 16ms Typical		Conducted Spurious Emissions:
	Antenna Impedance: 50 ohms	-57dBm <1GHz
Singletone Encoder/Decoder:		-47dBm > 1GHz
Nominal 847.5 Hz	Antenna connector: mini-uhf
		RX Attack Time: 60ms Typical
FCC Identifiers:
AZ492FT3802 (P2080A)
Industry Canada:
* Typically 5W in 8 ohms

VRS750 SPECIFICATIONS-UHF

GENERAL	TRANSMITTER	RECEIVER
Model: P2081A (403 – 470 MHz)	RF Power Out:	Intermodulation per EIA:
P2082A (450 – 512 MHz)
	275 mW to 2 W tunable	70 dB
Number of Channels: 1, T1=R1
Frequency:	Spurious and Harmonic	Hum and Noise:
Programmable, Synthesized Frequency	Emissions:
Channel
Channel Spacing:	-36 dBm < 1 GHz	-40dBm @ 25 kHz
	-30 dBm > 1 GHz	-35dBm @ 12.5 kHz
12.5/20/25 kHz
	Frequency Stability:	Reference Sensitivity(typical):
Operation Temp. Range:	±2.5 ppm @ 25 kHz	0.28µV (-118dBm) at 12 dB
	±2.5 ppm @ 12.5 kHz	SINAD
-30°C to +60°C
Primary Power:	Modulation Limiting(max):	Conducted Spurious Rejection:
13.8 VDC ± 20%, Negative Ground	±2.5 kHz @ 12.5 kHz	70 dB
	±4.0 kHz @ 20 kHz
	±5.0 kHz @ 25 kHz
DC Current Drain(max):	Audio Response: (from	Adjacent Channel Selectivity:
	6dB/octave pre-emphasis, 300 to
	3000 Hz)
120mA Receive	+1, -3 dB	60 dB @ 12.5 kHz
700mA Transmit @ 275mW		70 dB @ 25/30 kHz
1.20A Transmit @2W	Audio Distortion:
	3% Typical @ 1 kHz, 60%	Audio Response (0.3 – 3 kHz):
	maximum deviation
Squelch Operation: Private-Line		+1 to –3 dB
required for repeater access
	FM Hum and Noise: -40dB
Duty Cycle: Intermittent per EIA at		Audio Distortion
275mW		3% Typical @ Mobile Rated
		Audio*
	TX Attack Time: 14 ms Typical
PPI Sample time: 16ms Typical		Conducted Spurious Emissions:
	Antenna Impedance: 50 ohms	-57dBm <1GHz
Singletone Encoder/Decoder:		-47dBm > 1GHz
Nominal 847.5 Hz	Antenna connector: mini-uhf
		RX Attack Time: 60ms Typical
FCC Identifiers:
AZ492FT4848 (P2081A)
AZ492FT4849 (P2082A)
Industry Canada:

* Typically 5W in 8 ohms

List of Abbreviations and Acronyms

B-P	Base to Portable
CPS	Customer Programming Software
DPL	Digital Private Line
HT750	Transceiver internal to VRS750
HUB	Hang Up Box
ICM	In Car Monitor
ms	Millisecond
PAC	Portable Area Coverage
PL	Private Line
PPI	Portable Priority Interrupt
P-B	Portable to Base
RF	Radio Frequency
RX	Receive
SB	Serial Bus
SBEP	Serial Bus Expanded Protocol
Slm-net	Transceiver internal to VRS-EP
TOT	Time Out Timer
TX	Transmit
VIP	Vehicle Interface Port
VRS	Vehicular Repeater System
VRS-EP	Vehicular Repeater System - Expanded Protocol
VRS750	Vehicular Repeater System - Model 750

1. Introduction

Description

The ASTRO Spectra compatible Vehicular Repeater System - Model 750 (VRS750) is a mobile radio system component that provides on-site repeater capability between a portable radio and a base station. The VRS gives the portable user the equivalent range of a mobile radio with the flexibility of a portable. The VRS is not an ASTRO-capable radio; instead, it is designed to interface with an ASTRO Spectra mobile radio. It can only transmit and receive clear analog transmissions.

The VRS receives transmissions on the portable radio's transmit frequency with the proper access PL, and passes these portable signals to the mobile radio. The mobile radio re-transmits the signals to the base station on the mobile radio's transmit frequency. NOTE:These transmissions have the mobile's ID, not the portable's.

Similarly, base station signals received by the mobile radio are sent to the VRS and retransmitted to the portable radio. The VRS does not provide local repeater capability (received portable signals are not repeated on the portable receive frequency).

The VRS-to-portable and portable-to-VRS communications are limited to clear analog only. This is a simplex-only interface; the VRS cannot receive and transmit simultaneously. The base station-to-mobile and mobile-to-base communications protocol is not limited to analog only. Rather, this interface is limited by the features and functions of the ASTRO Spectra and the base.

Ordering Information

The VRS is a crossband repeater that operates on either UHF or VHF frequencies. The repeater cannot be operated with a mobile radio operating in the same band as the VRS unit.

The VRS RF platform is based on the HT750 synthesized transceiver. The VRS supports one channel whose frequency and channel spacing can be programmed in the field. The VRS remains a simplex repeater and as a result, the transmit frequency must be set equal to the receive frequency. The VRS receives its programming information from the ASTRO Spectra mobile at power-up. The ASTRO Spectra mobile supports the VRS programming fields via ASTRO Customer Programming Software (CPS). For more information, refer to “Programming,” Chapter ?.

The VRS is not compatible with ASTRO Spectra mobiles with the VSELP signaling type.

When integrating a VRS with an ASTRO mobile with a Siren/PA, an additional interface cable is needed (?). This cable allows the VRS to be connected to the Siren/PA. For more information, refer to "Installation," Chapter 4.

When integrating a VRS with an ASTRO mobile with Dual Control heads, an additional interface cable is needed (NKN6460A). This y-cable allows the VRS to be connected to the ASTRO mobile with two control heads. For more information, refer to "Installation," Chapter 4.

A separate antenna (not included) is necessary for use with the repeater. Typically, a onequarter (1/4) wave length antenna maximizes radiation efficiency when installed at the center of the vehicle roof. If it is necessary to mount the antenna on the vehicle’s trunk lid, an appropriate 3dB gain antenna should be used. See "Installation," Chapter 4, for details.

A filter for the battery lines (TLN5277B)is available for use with ASTRO Spectra mobiles. This filter can be used to prevent excessive alternator whine noise from being heard on the mobile speaker during VRS operation.

The VRS ships from the factory with the low output power setting at 275mW and a high output power setting of 2W. The low output power setting is the default setting. We recommend the LOW Transmit Power setting of 275mW for optimal performance. This output power provides the VRS with a similar range as the portable when attached to a mobile antenna. Any deviation from this setting could result in a loss of communication from the portable to the base.

The Global Tuning Tool (not included) can be used to tune the VRS output power in the field. For more information refer to “Tuning,” Chapter ?.

VRS Features

The VRS operates with the ASTRO mobile radio and contains the following integrated features:

o Automatic, multiple-unit, priority-resolution algorithm. o Portable priority interrupt (PPI) function.

o Conventional/trunked operation.

o Remote switch enable/disable capability for control charger interface. o Remote activation of emergency alarm feature.

o In-car monitor operation. o VRS mobile access tones.

o Mobile radio transmitter steering of up to eight modes via Private-Line (PL) code transmission from the portable radio.

o TX PL generator.

o Base repeater operation for two-frequency, simplex, fixed-repeater systems. o Mobile audio repeat.

All VRS features can be programmed in the field using ASTRO Spectra mobile CPS. For more information, refer to “Programming,” Chapter ?.

IMPORTANT NOTE: All ASTRO Spectra VRS systems with the same VRS RF transmit/receive frequency need to be CPS programmed identically to ensure proper operation. Failure to do so could result in erratic system operation.

The VRS does not have to be installed in the system for programming - only the mobile radio is programmed. If the VRS is not connected after programming the mobile system, an error message "ERR 12/10" will be displayed on the control head.

Mutually-Exclusive Features

The VRS IS NOT compatible with the following mobile radio features: o W3 Control Head is not supported with VRS

o VSELP signaling type

oData-VRS and data are not compatible on the same channel and cannot be used simultaneously. VRS should never be activated on a channel that has packet data enabled, and VRS mode steering channels should not have

packet data enabled. o Scan

o Over-the-Air Rekeying (OTAR) Rekey Request

o Message (from the Control Head)-Trunking or Conventional o Status (from the Control Head)-Trunking or Conventional

oEmergency Call-Trunking or Conventional-Emergency Call and VRS are mutually exclusive. Even if the mobile is programmed for Alarm and Call, when the Alarm case is exited, the mobile will not transition into Emergency Call while the VRS is activated. Likewise, if the mobile is in Emergency Call, the VRS cannot be activated. NOTE:When an

Emergency Alarm is received, the dispatcher may elevate that talkgroup to Emergency status.

o Reprogram Request-Trunking

o Repeater Access Control-Conventional o Mobile Single Tone-Conventional

o Seven-Tone Modat-Conventional o Motorcycle

o Consolette (Digital Remote and Tone Remote)

The following mobile radio features may be received but may not be initiated or responded to while VRS is enabled.

o Private Conversation -Trunking

o Call Alert-Trunking or Conventional

o Telephone Interconnect-Trunking or Conventional

oVoice Selective Call-Conventional

2.VRS Operation

General

The VRS is a crossband repeater that repeats either UHF or VHF portable transmissions though a VHF, UHF, or 800MHz ASTRO mobile. The repeater cannot be operated with a mobile radio operating in the same band as the VRS unit. In multiple-VRS sites, the VRS uses a priority algorithm to prevent other VRS units from repeating. In this mode, only the highest priority VRS will serve multiple portable users. This prevents interference problems associated with multiple VRS units in proximity to one another.

Control Unit

The VRS may be enabled/disabled from the ASTRO mobile radio's remote-mounted W4, W5, W7, or W9 control head (see Figure 1). The VRS button may occupy any of the

indicator button positions. Field programming determines the exact position. The VRS requires an ASTRO radio with a remote-mount control head.

Figure 1 Typical ASTRO Control Head with VRS

When the VRS is turned on, the indicator illuminates and, after transmitting the Single Tone burst, the words "VRS BOTH" (indicating the In-Car Monitor mode) will be displayed momentarily. The indicator remains on for as long as the VRS is on.

When the VRS unit is activated, it transmits Single Tone on the portable frequency, and assumes the priority (active) repeater state. The Single Tone frequency is fixed at 847.5 Hz. For proper operation, all VRS units to be used in the same system must be programmed with the same Single Tone frequency, as well as other VRS and ASTRO mobile features.

Press the VRS button to disable the VRS option. When the system is turned off and then back on from the control head, the VRS option returns to the state it was in immediately before the control head was turned off.

Vehicle Interface Ports

Another method of enabling/disabling the VRS option is through the use of a vehicle interface port (VIP). The field programmer selects which VIP to use and whether the input control voltage is to be high/ground or ground/high.

One use of VIP operation connects the VRS switch lead to a portable radio vehicular control charger, such as the AVA, SVA, MVA, or MTVA. Remove the portable from its charger pocket to automatically enable the VRS option. Replace the portable unit in its charger to disable the VRS option. A toggle switch on the portable unit charger allows the portable unit to be removed without enabling the VRS option.

NOTE: This requires an additional field modification kit, PLN1334A, which is not included with the VRS.

Turning the portable unit charger off, then on does not disable the VRS option. The VIP setting controls the on/off state of the VRS option. If the field programmer chooses the VIP option, pressing the VRS button on the control head will only cause the display to change momentarily to the In Car Monitor Mode ("VRS BOTH"). It will not enable or disable the VRS as previously described. It is still necessary, however, to select in CPSCPS an indicator button for the VRS if it is desired to have the indicator light when the VRS is enabled.

VRS Access

With the VRS on, press the portable radio's PTT button to begin transmissions. The VRS programming must include correct PL frequencies to allow the portable unit to access the option. The

VRS option receives signals with the correct PL, then uses the mobile radio to re-transmit the signals. The control head's XMIT indicator lights during the re-transmission.

The VRS re-transmits received mobile signals as explained in the "Mobile Audio Repeat" paragraph on page 7. Note that the XMIT indicator does not light when the VRS is transmitting to the portable.

To transmit directly to the other portable units, turn off the portable transmit PL. This allows you to talk around the VRS without transmitting on the mobile channels.

In-Car Monitor

The "In-Car Monitor" (ICM) feature is for use in a two-man operation where one user (user 1) is out of the vehicle while the other (user 2) remains in the vehicle. This allows user 2 limited access to both mobile and portable communications when the VRS is on, even when the repeater is the priority unit. ICM operation is set to BOTH.

ICM Transmissions

VRS BASE:

Press the mobile's PTT to transmit on the frequency corresponding to the mode shown on the control head’s display. If this mobile’s VRS is the priority unit (in delay state zero), the VRS unit will then become non-priority upon the mobile PTT. If you press the mobile's PTT during portable-to-base VRS activity, a talk-prohibit tone sounds and the mic audio is disabled.

VRS BOTH:

Press the mobile's PTT to transmit simultaneously on the frequency corresponding to the mode shown on the control head's display, and the portable frequency. Use the ASTRO CPS to enable the VRS TX PL generator option to transmit with the proper PL frequency. If you press the mobile's PTT during portable-to-base VRS activity, a momentary talkprohibit tone sounds and the microphone audio is disabled.

When using VRS BASE or VRS BOTH mode, all mobile transmissions are on the mode that is shown on the control head's display. If the VRS is currently steering to another mode, that steered mode will be displayed on the control head. Any mobile transmissions will be on that new mode until the portable steers the VRS back or the mode rocker switch is used to change modes. If the mode rocker switch is used to change modes, the portable user will not be made aware of this mode change. With Ack Tones are enabled, the portable user will hear a "bad" tone if the mode is changed during the transmission.

VRS Reception

The VRS option has no effect on mobile radio squelch control or normal mobile radio reception. The VRS portable unit's squelch setting is not user adjustable. Portable audio is heard from the mobile speaker of the priority VRS unit as shown in the following table: Mobile Microphone Portable Audio Heard from Mobile Speaker

On HUB	PL*
Off HUB	CSQ

* = any valid repeater access PL

Repeated portable transmissions will always be heard from the mobile speakers. Portable transmissions without proper PL will only be heard from the mobile speaker if the microphone is off HUB.

Mobile Audio Repeat

The VRS transmits to the portable when audio unmutes the mobile speaker. This allows the user to set the monitor button "on" to defeat the coded squelch requirements of the mobile radio on a base-to-portable transmission or "off" to prevent the VRS from

repeating base-to-portable (HUB will also disable this), unless the coded squelch requirements of the mobile radio are met. Button presses (that is, Volume, Mode, etc.) on the priority mobile unit will also be transmitted by the VRS.

3. Operation of VRS

Options

The following sections describe the operation of CPS field-programmable options of the VRS. This includes information about when to use an option and compatibility between options.

Base Repeater

For two-frequency simplex systems using a fixed-site repeater, you can enable the base repeater option. This adds 300 ms of delay to the prioritization routine to account for the fixed repeater attack time. This allows non-priority mobiles to detect any priority mobile in the system through the base repeater.

Mobile Detector

The Mobile Detector feature allows the user to operate VRS units with two-frequency simplex dispatch systems without a base repeater. This feature allows the automatic multi-unit priority resolution algorithm to function in the above scenario. When this feature is activated by the CPS, a non-priority VRS will send a message to the mobile to enable a "Listen Around" feature when a proper portable PL is received.

"Listen Around" switches the mobile radio's receive frequency to match that of its transmit frequency of the steered mode. The non-priority VRS will count down in priority if its corresponding mobile does not detect the repeated transmission on the "Listen Around" frequency. When the portable is dekeyed, the non-priority VRS will send a second message to the mobile to disable "Listen Around" and return to normal operation. This feature does not use any additional user modes in the mobile.

NOTE: The Mobile Detector feature only works on conventional modes. Trunked modes will be unaffected.

VRS Transmit PL Generator

The transmit PL generator, when enabled, causes the VRS to transmit (base-to-portable), with specific field programmable PL tones. The selected VRS transmit PL frequency cannot be the same as any of the VRS receive PL frequencies that the portable uses to access the vehicular repeater.

VRS Mode Steering

The VRS steering option gives the portable operator the ability to select the current mobile radio mode via PL tones. The total number of Mode-Steered modes can not exceed eight (including emergency, message, and status). The operator may program as many as eight such tones, along with corresponding mobile mode numbers, into the

VRS. The portable operator sets the channel or mode select switch to the position corresponding to the desired mobile mode and keys up the portable. The VRS unit decodes the PL tone and steers the mobile radio to the desired mode. There are two types of steering supported: Transmitter Steering/Receiver Latching, and Transmitter Steering/Receiver Steering.

NOTE: If mode steering is not selected during CPS programming, the programmer will need to enter the repeater access PL, which corresponds to a single access PL with select mode steering.

Steering Types

o <Transmitter Steering/Receiver Latching> - On portable-to-base repeating, the mobile radio is steered to the proper mode as determined by the received PL from the portable. When the portable dekeys, the condition to repeat ceases, and the mobile radio remains on this mode. Thus, all future base-to-portable repeating is heard via the mobile mode last steered by the portable.

The mobile control head will display the steered/latched mode. If, sometime after this operation and while no repeat is occurring, the ICM user keys the mobile with the micropnone's PTT button, the mobile will now transmit on the latched mode that is displayed on the control head. If, however, the in-car-monitor (ICM) user changes the selected mode using the mobile's mode rocker switch before pressing the mic PTT, the mobile will now transmit on the new selected mode.

NOTE: For the above type of steering, the portable user will be able to steer back to the selected user mode on the control head by programming one PL destination for Sel-Mode. However, the selected mode can be changed by the rocker mode switch.

o <Transmitter Steering/Receiver Steering> - On portable-to-base repeating, the mobile radio is steered to the proper mode as determined by the received PL from the portable. When the portable dekeys, the condition to repeat ceases, and the mobile radio remains on this mode for 6 seconds. During this 6 seconds, the VRS waits for a repeatable base-to-portable transmission to be received.

•If a base-to-portable transmission is not received, the mobile will return to the last mode selected by the control head's rocker switch (current user-selected mode).

•If a base-to-portable transmission is received during the 6-second timer, the timer will be reset back to 6 seconds and start over at the end of the transmission.

•If the portable is keyed during the 6 seconds, the VRS will handle the destination PL accordingly and reset the timer. If the 6-second timer has not expired, no repeat is occurring, and the ICM user keys the mobile with a microphone PTT, the mobile will transmit on the steered mode and the 6-second timer will start over at the end of the transmission.

Steering Destination Types

There are five types of actions, or "steering destination types," that the VRS can be programmed to perform as a result of receiving a portable transmission with the specified PL:

NOTE: Each receive PL can only be used once and can only be programmed with one type of steering destination (for example, a single PL cannot be programmed to both change the mobile mode and send a message.)

Zone/Chan

The VRS will command the ASTRO mobile to change to the mode programmed by the CPS. Once the mobile has steered, it will follow the conventions of the type of steering selected (for example, Transmitter Steering/Receiver Latching).

Select Mode

The VRS will command the ASTRO mobile to return to the last mode selected by the rocker switch on the control head. If the portable user has steered to another mode, and the selected mode is changed in the car, the steering will be canceled until the VRS receives another mode steering PL.

Emergency Alarm

The VRS will initiate an Emergency Alarm through the ASTRO mobile, if the mobile is programmed for this type of Emergency, in the same manner as if the Emergency button on the control head were pressed. The type of Emergency (trunked or conventional) depends on the currently selected mobile mode, (trunked or conventional, respectively). The VRS will only generate an Emergency, not perform a portable-to-base audio repeat, while the portable is transmitting on an "Emergency request" channel. This feature is typically implemented in the portable, using a one-touch button that has been programmed for Emergency-revert to a channel with the proper PL.

Although the portable generates MDC tones, the VRS cannot decode MDC. Instead it responds to the PL of the portable mode on which the Emergency MDC tones are transmitted. All of this is transparent to the user.

Message

The VRS will command the ASTRO mobile to send out an CPS-programmed message on the mode currently displayed on the control head, in the same manner as if the request to send a message had been generated using the control head. The VRS will send out only one message per received portable signal. No mode steering will occur; the currently steered/latched mode and the selected mobile mode will remain as they were before the request to send a message was received.

If the message selected is valid, the VRS will transmit to the portable the mobile tones indicating whether or not the valid message was acknowledged. If the message selected is invalid, (either incorrectly programmed in CPS or not a valid message for the currently displayed mode), the VRS will send a low-pitched alarm tone to the portable.

To generate a message request, the portable user would:

o select the channel on the portable programmed for the message request, o momentarily press the PTT button,

o wait for the confirmation tone, and

o return the channel selector to a voice channel.

The VRS will not perform a portable-to-base audio repeat while the portable is transmitting on a "message request" channel.

NOTE: A message cannot be generated from the control head while the VRS is activated.

Status

The VRS will command the ASTRO mobile to send out an CPS-programmed status on the mode currently displayed on the control head, in the same manner as if the request to send status had been generated using the control head. The VRS will send out only one status per received portable signal. No mode steering will occur; the currently steered/latched mode and the selected mobile mode will remain as they were before the request to send a status was received.

If the status selected is valid, the VRS will transmit to the portable the mobile tones indicating whether or not the valid status was acknowledged. If the status selected is invalid, (either incorrectly programmed in CPS or not a valid status for the currently displayed mode), the VRS will send a low-pitched alarm tone to the portable.

To generate a status request, the portable user would:

o select the channel on the portable programmed for the status request, o momentarily press the PTT button,

o wait for the confirmation tone, and

o return the channel selector to a voice channel.

The VRS will not perform a portable-to-base audio repeat while the portable is transmitting on a "status request" channel.

NOTE: A status cannot be generated from the control head while the VRS is activated.

Time-Out Timer

The Time-out Timer (TOT) duration value sets the maximum allowable time for a base- to-portable transmission. The VRS TOT may be set to 30, 60, 120 seconds, or disabled. When a unit times out, it counts up to delay state one. This removes it as the priority unit.

VRS Single Tone

When the VRS unit is enabled, it transmits an audible tone (Single Tone) for 700 mS which is used by other VRS units for the automatic prioritization routine. The Single Tone frequency is fixed at 847.5 Hz.

VRS Mobile-TX Acknowledgment Tones (Conventional Only)

When this option is enabled, the VRS transmits a 750 Hz feedback tone after it has received a repeatable message on the portable frequency. This signals the portable operator that the transmission was received. If the repeated message was cut short due to the mobile TOT being exceeded or the mobile channel being changed during the repeat, a lower-pitched tone (304 Hz) sounds. If the portable user does not hear a tone after completing a transmission, the portable is either out of range of the repeater or there is no priority repeater in the area.

See "VRS Mobile Trunking Tones (Trunking Only)" on page 26 for a description of trunking acknowledgment tones.

Flashing Display

The Flashing Display feature causes the display on the control head to alternate between the current mode and "VRS BOTH." This feature is used primarily when the VRS enable/disable button does not have an indicator light or when VIP activation is used. This feature is normally disabled in CPS. The length of time "VRS BOTH" is displayed

every 6 seconds is determined by the "temporary message display timer" value. This value (from 250 to 6250 ms [default = 1000 ms]) can be programmed by the CPS. It is in the RADIO WIDE DISPLAY OPTIONS screen (D, C, F from the main CPS screen).

Repeater PPI

The Repeater Portable Priority Interrupt (PPI), when enabled, causes a base-to-portable transmission to be interrupted every 1 second in trunked mode or 2 seconds in conventional mode so that the repeater can search for a portable radio signal. (These times are programmable and may be changed to 500ms for trunked or 500ms for conventional modes). This interruption may be heard on the portable as a "clicking" noise, but PPI is necessary to give the portable user priority over base-to-portable transmissions, for the self-clearing function of the automatic priority resolution feature, and to allow portable users in trunked mode to break in during system hang time to prevent loss of voice channel. This feature may be disabled through CPS.

Quick-Key

This feature allows the portable user to determine the status of the mobile trunking system. The feature is initiated by a short press of the portable's PTT that is long enough for the VRS to key the mobile and access the trunking system, for less than 1 second in duration.

4. Installation

When selecting the location for the VRS, make certain that there is sufficient clearance for routing the T-cable and the antenna cable to the front of the unit.

VRS Installation

The standard VRS is installed using the HKN6153A interface cable. The molded DB-25 end connects to the ASTRO front connector. The DB-25 end with the plastic jacket connects to the VRS (see Figure 2).

Figure 2 Installing the VRS to an ASTRO Mobile

If an external Siren/PA is to be used, the option xxxxAA must be ordered which replaces the HKN6153A cable with a HKN6154A cable, or a separate HKN6154A cable must be ordered. To install, plug the "T" side of the HKN6164A cable to the Siren/PA. Replace the mounting screw on the HKN4363B cable with the double length screw. Plug this side into the "T" cable. Plug the DB-25 end of the HKN6154A into the VRS (see Figure 3). Figure 3 Installing the VRS with an External Siren/PA

Mobile Radio Operation and EME Exposure

To assure optimal radio performance and that human exposure to radio frequency electromagnetic energy is within guidelines referenced earlier in this document, transmit only when people outside the vehicle are at least the minimum lateral distance away from

a properly installed, externally-mounted antenna. Table ? lists the minimum lateral distance for the VRS 750:

Rated Power of Vehicle-installed	Minimum Lateral Distance from
Mobile Two-way Radio	Transmitting Antenna
Less than 7 Watts	8 Inches (20 Centimeters)

VRS Antenna Installation

Recommended mobile antenna installations are limited to metal body vehicles at the center of the roof and center of the trunk deck locations.

Install the antenna to be used with the VRS according to the instructions supplied with it by the manufacturer (an antenna is not included with the VRS models). Mount the antenna as far from the mobile radio antenna as possible, but never less than three feet. An ideal configuration would be a roof-mounted mobile radio antenna and a trunkmounted VRS antenna. Connect the antenna cable mini-UHF connector to the antenna jack on the rear of the VRS unit. A mini-UHF crimp connector is provided with each VRS750 unit for easier installation with a pre-existing antenna.

VRS750 Programming

The user selectable operating parameters for the VRS750 reside in the ASTRO mobile EEPROM during normal operation. The EEPROM located in the VRS750 holds the tuning parameters. The VRS750 programming windows reside in ASTRO Spectra CPS and are accessible when the “VRS-EP Option” is enabled in CPS under the Radio Configuration->Radio Wide->Advanced window (see Figure 4).