A Telephone-Based Remote-Controlled Radio Receiver
Posted: Tue Jun 30, 2009 10:31 am
I've been meaning to post this for a long, long time...
It's a DTMF-controlled radio that back-hauls audio through telephone lines cirrca 1993. I used to have a network of these scattered across the country.
A modified Radio Shack STA-300 serves as the basic receiver.
This is the telephone interface:
By decoding DTMF tones and placing opto isolators across the keyswitches the front panel can be remotely controlled.
This is the transmit/receive filter. Audio from the radio feeds the telephone hybrid. Incoming DTMF tones are split in the hybrid and filtered prior to DTMF decoding.
https://www.ka-electronics.com/images/D ... it_Rcv.JPG
A pair of Prem SPT-183 transformers are used to split incoming and outgoing audio. Also shown are the ring detector front-end and the line seize relay.
https://www.ka-electronics.com/images/D ... erface.JPG
Auto answer logic seizes the line and releases it on hang-up. I "borrowed" this from Gentner.
https://www.ka-electronics.com/images/D ... Answer.JPG
This is a DTMF decoder using a TDK 202 IC.
https://www.ka-electronics.com/images/D ... ecoder.JPG
The DTMF is decoded and drives opto isolators.
https://www.ka-electronics.com/images/D ... erface.JPG
The opto isolators parallel the radio's switch contacts.
https://www.ka-electronics.com/images/D ... Keypad.JPG
This little baby has apparently made me a "prominent" celebrity (outlaw?) in the Second Circuit Court of Appeals and now the US Supreme Court.
Tags: Telephone Coupler, Telephone Hybrid, Remote Control Radio Receiver, DTMF, Touch Tone, Listen Line, Broadcast Monitoring, Advertising Fraud, Affidavit, Air Check, Off Air Monitoring, Broadcast Log, Infinity Broadcasting, CBS, Sony Corporation, Jefferson Pilot, Wayne Kirkwood, Infinity v. Kirkwood, Fair Use, Copyright Infringement, SESAC, ASCAP, BMI, Premier Broadcasting.
It's a DTMF-controlled radio that back-hauls audio through telephone lines cirrca 1993. I used to have a network of these scattered across the country.
A modified Radio Shack STA-300 serves as the basic receiver.
This is the telephone interface:
By decoding DTMF tones and placing opto isolators across the keyswitches the front panel can be remotely controlled.
This is the transmit/receive filter. Audio from the radio feeds the telephone hybrid. Incoming DTMF tones are split in the hybrid and filtered prior to DTMF decoding.
https://www.ka-electronics.com/images/D ... it_Rcv.JPG
A pair of Prem SPT-183 transformers are used to split incoming and outgoing audio. Also shown are the ring detector front-end and the line seize relay.
https://www.ka-electronics.com/images/D ... erface.JPG
Auto answer logic seizes the line and releases it on hang-up. I "borrowed" this from Gentner.
https://www.ka-electronics.com/images/D ... Answer.JPG
This is a DTMF decoder using a TDK 202 IC.
https://www.ka-electronics.com/images/D ... ecoder.JPG
The DTMF is decoded and drives opto isolators.
https://www.ka-electronics.com/images/D ... erface.JPG
The opto isolators parallel the radio's switch contacts.
https://www.ka-electronics.com/images/D ... Keypad.JPG
This little baby has apparently made me a "prominent" celebrity (outlaw?) in the Second Circuit Court of Appeals and now the US Supreme Court.
Tags: Telephone Coupler, Telephone Hybrid, Remote Control Radio Receiver, DTMF, Touch Tone, Listen Line, Broadcast Monitoring, Advertising Fraud, Affidavit, Air Check, Off Air Monitoring, Broadcast Log, Infinity Broadcasting, CBS, Sony Corporation, Jefferson Pilot, Wayne Kirkwood, Infinity v. Kirkwood, Fair Use, Copyright Infringement, SESAC, ASCAP, BMI, Premier Broadcasting.