Re: [Discuss-gnuradio] Car alarms and garage door openers

[Johnathan Corgan]

Johnathan Corgan wrote:

> I looked up the FCC ID for mine.  It's allocated for use between 314.5
> and 315.5 MHz, which is I'm sure to allow cheap oscillators to be used.

Woah...the FCC search has a "detail" option that comes up with a list of
PDFs describing the whole key fob (URL will wrap I'm sure):

https://gullfoss2.fcc.gov/prod/oet/cf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=102455&fcc_id='CWTWB1U331'

In my case:

                          CIRCUIT DESCRIPTION
TRANSMITTER

The hand-held RF transmitter consists of the housing, three or four
control buttons, microcontroller, an UHF oscillator (Colpits
configuration) and a 3 volt battery. The microcontroller uses an
internal oscillator running at 4.0 MHz, and the RF oscillator uses a SAW
based oscillator to resonate at 315.0 MHz. The modulation format used
will be ASK, with a Rolling/Manchester code data format. Once the user
presses a button power is applied to the microcontroller which turns the
RF oscillator on and off at the rate of the Rolling/Manchester code data
being sent. The signal is then sent to the receiver module via RF data
transmission. The module will then act upon the RF data received and
will perform certain functions in correspondence to which transmitter
button is pressed.


-Johnathan, AE6HO