YalekW
Member
- Joined
- Jun 16, 2012
- Messages
- 95
So Ive been scanning for a really long time, and ive encountered every single type of telemetry signal I can find, from v.22 modems to many forms AFSK, custom-made pager signals in europe (on the spyservers), QAM glenayres (including one right next to this one >> 454.425 with KNKH915 << not listed in the frequencies of that license, thanks FCC). So techincally you could call me a radiomodem phreak now.
But theres one that a I REFUSE to understand, and its in downtown chicago >> and we have on the sigidwiki named as "PSK paging link" (also known as PURC but thats not the right title).
The actual tones this thing uses use a distorted idle thats supposively not even idle, V.27ter modulations (the data is used in all the modes).
I have tried so hard to get a proper Phase plane out of this and the page is supposively describing 8PSK but I think its trying to use MSK. I need further confirmation though. It does use MDC1200 as its beginning and ending sequences.
It also does a Bell 202/AFSK PL every so often >> and thats decodable by hand. There is no morse ID, and there is instances where this transmitter does its MDC1200 sequences in a secret fashion, and then glitches the main Bell202/AFSK PL and "glitches" the main signal before ending. Data comes back when it has completed its "secret id".
Does ANYBODY from this area know what modulations its using, as it seems to be putting the POCSAG pulses as phases instead. I also had somebody put up a live stream of it on Icecast a year back.
You have to be in downtown chicago to be able to receive this though, sometimes no data transmits, or sometimes (maybe on new years like this date), theres nothing but absolutely non-stop POCSAG pages going through it >> THROUGH V.27ter sub-modes.
But theres one that a I REFUSE to understand, and its in downtown chicago >> and we have on the sigidwiki named as "PSK paging link" (also known as PURC but thats not the right title).
The actual tones this thing uses use a distorted idle thats supposively not even idle, V.27ter modulations (the data is used in all the modes).
I have tried so hard to get a proper Phase plane out of this and the page is supposively describing 8PSK but I think its trying to use MSK. I need further confirmation though. It does use MDC1200 as its beginning and ending sequences.
It also does a Bell 202/AFSK PL every so often >> and thats decodable by hand. There is no morse ID, and there is instances where this transmitter does its MDC1200 sequences in a secret fashion, and then glitches the main Bell202/AFSK PL and "glitches" the main signal before ending. Data comes back when it has completed its "secret id".
Does ANYBODY from this area know what modulations its using, as it seems to be putting the POCSAG pulses as phases instead. I also had somebody put up a live stream of it on Icecast a year back.
You have to be in downtown chicago to be able to receive this though, sometimes no data transmits, or sometimes (maybe on new years like this date), theres nothing but absolutely non-stop POCSAG pages going through it >> THROUGH V.27ter sub-modes.