wowbagger wrote:I think he is implying you should stick with audio paging, rather than RF.
Ahh, I get it. The project I had in mind was actually for bowling alley mechanics. The place is currently using two-way radios, but the mechanics are surrounded by extremely noisy machines, so they're currently stuck with solutions like wearing earbuds under gunmuffs to hear, and for some reason, even with that they miss a fair amount of calls. It's mostly a one-way solution; the only time they really talk back is when they ask for a repeat. Hence my interest in a text-based solution.
What about going to a cellular text messaging solution? Or an 802.11b solution and some form of instant messaging on a PDA?
I've thought about Nextels, which would actually be ideal... Except that the "client" is a total tightwad. :rolleyes:
Even assuming you do, getting cheap pagers on that frequency, whatever it is, is going to be hard.
This is actually the one part of this idea I have under control. What inspired it was noticing that the set of used (but working!) VHF POCSAG pagers I picked up was still sitting in a box about a year later, with no real use. I believe they cover 151-159, hence my interest in using MURS.
k2hz wrote:Paging and digital emissions are allowed on MURS but finding a transmitter certified for MURS use and digital emissions may be a problem.
Pardon my ignorance: when a normal ol' MURS HT is "certified," does the cert mean that it's OK for MURS in general, or that it's approved specifically for FM use (only)? I've had good luck recovering data from an audio jack (and processing it at POCSAG) even after passing through the discriminator... So I thought about trying in reverse: dropping the data rate to 512 baud (it might see 30 pages sent in a day, to a whopping 2 pagers, so it's not like I need to keep that baud rate high to support everyone), and then, doing the same thing you do with a crappy TNC on a crappy ham rig: feed the output into the mic jack. Obviously this isn't as desirable as a radio with a dedicated FSK input, but I wonder whether this is legal or not on MURS?
MURS stations may transmit voice or data signals as permitted in 47 CFR 95.631(j).
Googling this reveals:
(j) A MURS transmitter must transmit only emission types A1D, A2B, A2D, A3E, F2B, F1D, F2D, F3E, G3E. Emission types A3E, F3E and G3E include selective calling or tone-operated squelch tones to establish or continue voice communications. MURS transmitters are prohibited from transmitting in the continuous carrier mode.
My understanding of the emission types is lacking... Would POCSAG fall as "F2D" (frequency-modulated, digital (subcarrier??), data/telemetry)?
MURS transmitters may not be operated in the continuous carrier transmit mode.
This would just be occasional transmissions... I assume this isn't getting at the same thing as the ham "no one-way transmissions" sort of thing, but rather, "You shall not run a transmitter 24/7..." type thing?
This includes monitoring the transmitting frequency for communications in progress and such other measures as may be necessary to minimize the potential for causing interference.
This part might be tricky... I had in mind that the user, who wouldn't be technically-oriented, would type in a message, hit Enter, and have it transmitted. I suppose I could just feed the audio through (and mute when transmitting!), but I can see them encountering static and turning it down. Would simply implementing BCLO work? (It's worth noting that this is for a place in the middle of nowhere, and it'd be in-building, so the odds of external interference are very slim... But I want to make sure that this would be totally legal in any event.)