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Digital Voice Conversion Method

From The RadioReference Wiki

Digital Voice Conversion Method

Developed by: Joseph A Cardani

Objective

A method to recover digital voice on public safety APCO-25, ProVoice and Aegis digital radio systems.

Process

A communication receiver’s 10.7 MHz IF is mixed with a constant signal from an RF generator to produce an RF signal that is directly connected to the antenna input of an APCO P-25 or M/A-COM ProVoice/Aegis capable 2-way radio. This will allow digital voice decoding of any signal that is tuned on the communications receiver.

Benefits

  • The method is not band dependent – any channel that can be tuned by the communications receiver can be decoded. Other methods, such as a dedicated 2-way radio, can only operate on 800 MHz, UHF, etc.
  • The 2-way digital radio provides excellent specifications and vocoding versus a consumer grade scanner.
  • Trunk tracking is not performed by the 2-way radio; it is done by 3rd party software. This bypasses any legal issues with the equipment vendor. In addition, the 2-way radio is programmed conventionally with transmit disabled so there is no risk of accidentally transmitting on the frequency.

Components

Communications Receivers:

  • ICOM R-7000 or R-7100 or R-8500 or R-9000 (all have 10.7 IF output)

NovaSource M2 RF Generator: http://www.nova-eng.com

  • NS2-0800104 for 800 MHz operation
  • NS2-0320104 for UHF operation

Minicircuits Coaxial Frequency Mixer: http://www.minicircuits.com

  • ZAD-2 for 800 MHz operation (rated to 1 GHz)
  • ZAD-1 for UHF operation (rated to 500 MHz)

Diagrams

Flowchart1.gif


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Parts List

1	NovaSource M2 RF Generator @				$699.00
1	Minicircuits ZAD-1 or ZAD-2 Mixer &			$43.95 to $49.95
1	DC Block (Model 8080)*					$49.00
1	SMA/M to BNC/M Cable (Model RFW-5366-12)*		$18.00
1	BNC/F to SMA/F Adapter (Model 5014)*			$22.00
1	RCA/M to BNC/F Adapter (Cat # 278-280 or 278-301)**	$3.99
2	BNC patch cords (BNC/M both ends)	
@ Available from Nova Engineering http://www.nova-eng.com 1-800-341-NOVA
& Available from Minicircuits http://www.minicircuits.com 1-718-934-4500 
* Available from Sun Moon Electronics http://www.sunmn.com 1-800-715-4396
** Available from local Radio Shack

Connections

A sample setup using a Motorola ASTRO Saber.

Step 1 -- Connect the RCA/M to BNC/F adapter to the 10.7 IF output of the ICOM receiver (this is a female RCA jack).

Step 2 -- Connect the DC block to the adapter above.

Step 3 -- Connect one BNC to BNC cable from the DC block to the IF input of the Minicircuits mixer.

Step 4 -- Connect the SMA/M to BNC/M cable from the NovaSource RF Generator (SMA/F jack) to the LO input of the Minicircuits mixer (BNC/F jack).

Step 5 -- Remove the antenna from the Astro Saber and connect the BNC/F to SMA/F adapter to the antenna input (SMA/M jack)

Step 6 -- Connect the other BNC patch cord from the BNC/F to SMA/F adapter that is attached to the Saber to the RF output of the Minicircuits mixer (BNC/F jack).