We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Topics - MrGuts10

Pages: [1]
1
Hi everyone,

All-digital AM radio (NRSC MA3) is an accepted, but not widely used, standard. It could make the AM broadcast band better suited for music and performance, instead of just talk. The entire channel can either be devoted to near FM-quality audio, or can be divided into subchannels. All-digital AM also plays well with existing channel allocations, by staying confined to 10 kHz (corrected) spacing instead of bleeding over to adjacent channels as current IBOC HD is prone to do.

As far as I know, 820kHz WWFD-AM radio, based in Frederick MD, is the only fully digital AM broadcast radio station in the US. I for one would like to examine its packet structure and other aspects of digital broadcast signaling.

I am requesting that any SDR enthusiasts based around Mayland or Washington DC make I/Q recordings of WWFD and share them publicly so that the rest of us can study the format. Here is something to shoot for:

- I/Q samples MUST be recorded, not just Q-branch, so that symbol information is preserved
- on-air digital WWFD-AM MUST be recorded, not the repeater on WWFD-FM
- recording SHOULD cross the top of an hour (to include a time hack and station call)
- sample passband MUST be 10 kHz or wider, centered on 820 kHz
- sample rate MUST be greater than 2x the passband (faster than 20,000 samples per second)
- it is RECOMMENDED the sample passband be 22 kHz
- it is RECOMMENDED the sample rate be 45,000 samples/sec
- recording session SHOULD be about 300 seconds or longer
- share your recording publicly on GitHub or similar service
- notify this HFUnderground thread
- it is RECOMMENDED the recording be accompanied with a description of date, time of day, approx QTH, and equipment setup
- notify project https://github.com/theori-io/nrsc5 (for whom I do not speak)
- a 300 sec recording should come in under 100 MBytes, assuming 32 bits/sample and the recommended passband and sample rate

Recordings from various times, locations, signal conditions and equipment setup would be welcome. There is room for a lot of people to get involved here! I hope the all-digital AM format becomes more widely adopted in the US.

Please help make this request better with your suggestions.

Thank you!

Pages: [1]
HFUnderground T-Shirt
HFUnderground T-Shirt
by MitchellTimeDesigns