search

theori-io / nrsc5

NRSC-5 receiver for rtl-sdr
Other
796 stars 100 forks source link

Implement AM all-digital mode (MA3) #240

Closed argilo closed 4 months ago

argilo commented 4 years ago

The AM receiver only supports the hybrid mode (MA1) currently. At least one station (WWFD in Frederick, Maryland) is using the all-digital mode (MA3), so it would be nice to be able to receive it. It would be very helpful to have an I/Q recording of this station.

argilo commented 4 years ago

With some help from N3JLY who has a KiwiSDR (http://sdr.hfunderpants.com:8074/) near WWFD, I was able to make a couple recordings:

  1. https://drive.google.com/file/d/1acEfDG5J1BO3sgoSiIXaxLgO6Zc9-YZz/view?usp=sharing
  2. https://drive.google.com/file/d/1_yH5qODR5-zPOKVtMgHRDjDRZkuNimtE/view?usp=sharing

The following GNU Radio flow graph can be used to convert these I/Q WAV files to .cu8 files at a sample rate of 1488375 for use with nrsc5:

https://drive.google.com/file/d/1U3hg5LU8Bihs33-J980KkpzRmT6dbJ4Z/view?usp=sharing

The flow graph also has a disabled section which can be used to transmit the signals using a HackRF. I used this to verify that the recordings were good by playing them back to my Sangean HDT-20 receiver.

cbmira01 commented 2 years ago

Looks like WWMG in Egypt Lake FL, and WFAS in White Plains NY are operating all-digital MA3 also: https://en.wikipedia.org/wiki/WMGG https://en.wikipedia.org/wiki/WFAS_(AM)

argilo commented 4 months ago

MA3 is implemented in #344.

cbmira01 commented 4 months ago

Clayton,

Thanks for your work on this all-digital AM demonstration. I hope it helps raise the awareness of MA3 as a way to extend the usefulness of the MF broadcast band.

On Sun, May 5, 2024 at 1:50 AM Clayton Smith @.***> wrote:

MA3 is implemented in #344 https://github.com/theori-io/nrsc5/pull/344.

— Reply to this email directly, view it on GitHub https://github.com/theori-io/nrsc5/issues/240#issuecomment-2094643041, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABWMUDPRJTD5X4YSBVUYOG3ZAXCDLAVCNFSM4P6HAFHKU5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TEMBZGQ3DIMZQGQYQ . You are receiving this because you commented.Message ID: @.***>

ferrellsl commented 4 months ago

This is a bit off-topic, but I heard a rumor that iHeart had stopped all digital AM broadcasts. Is this true or just a nasty rumor?