Droitwich 198 kHz Radio 4
Posted: Tue Sep 05, 2023 8:21 pm
The clueless BBC have decided to close down the 198 kHz Radio 4 Long Wave transmitter next year. This is a really stupid decision, since the 198 kHz frequency is traceable to the National Physical Laboratory, and is accurate to thirteen digits. I've used it as a standard for years, since it's usually easier to receive than the MSF 60 kHz transmitter (even though the MSF accuracy is ~10 times better!).
I've used it - divided down - as the timebase for Medium Wave transmitters for years. I even modified my original homebrew standard signal generator from receiving the old 200 kHz signal (more easily divided to something useful) to handle the 198 kHz frequency when it was changed in the late '70s!
The 198 kHz signal also carries its own radio data - a bit like a slow version of RDS - and there's an interesting paper on decoding it (and what it's used for) at https://www.nxp.com/docs/en/application-note/AN1597.pdf which includes details of how to build your own decoder!
There is an online petition at https://chng.it/LMbdTQJ4DV to keep the 198 kHz rig going. If you have the slightest care for our radio heritage, please sign it!
I've used it - divided down - as the timebase for Medium Wave transmitters for years. I even modified my original homebrew standard signal generator from receiving the old 200 kHz signal (more easily divided to something useful) to handle the 198 kHz frequency when it was changed in the late '70s!
The 198 kHz signal also carries its own radio data - a bit like a slow version of RDS - and there's an interesting paper on decoding it (and what it's used for) at https://www.nxp.com/docs/en/application-note/AN1597.pdf which includes details of how to build your own decoder!
There is an online petition at https://chng.it/LMbdTQJ4DV to keep the 198 kHz rig going. If you have the slightest care for our radio heritage, please sign it!