Comment 108G5 Re: appearance

Story

Tiny FM transmitters deliver news and entertainment inside Syria

Preview

appearance (Score: 1, Interesting)

by Anonymous Coward on 2016-01-01 14:11 (#ZB1K)

Kudos to the developers, but really, it looks like a piece of military or ham gear with heat sink fins on three sides of the case. I'm assuming that operating one of these in hostile territory is asking for trouble -- like a swat team through your door. Couldn't they have made it look like a boom box or really almost anything else that looks less incriminating?.
Other points the article didn't mention -- output power (probably illegal if over 100mW?)
Also, isn't it easy to locate a transmitter with some minimal sleuthing gear, like a dipole antenna?

Re: appearance (Score: 2, Insightful)

by evilviper@pipedot.org on 2016-01-01 19:12 (#ZBPH)

You're suffering from a severe lack of context... Syria is several years into a massive and brutal civil war.
didn't mention -- output power (probably illegal if over 100mW?)
Do you know anybody who has been executed for operating a transmitter over the legal power limit? Simple survival is the major pressing concern for everyone there, right now.
operating one of these in hostile territory is asking for trouble -- like a swat team through your door.
That's where the "work autonomously" bit comes in. You go set it up, turn it on, and leave. Someone tracking it down will find a few hundred dollars worth of equipment, and no way to trace it back to anybody.

Re: appearance (Score: 0)

by Anonymous Coward on 2016-01-02 02:21 (#ZCDR)

Right, the article did say,
> Connected to a solar panel, a PocketFM transmitter can theoretically work autonomously for long periods of time.

In that case, and since it already has a cell radio (to get text messages), why does it have a screen? Wouldn't a smart phone be a better way to initialize it -- then take the phone with you after getting the transmitter running?

Seems like there must be more to the story. For example the autonomous operation is only "theoretical"?

Re: appearance (Score: 1, Interesting)

by Anonymous Coward on 2016-01-10 21:06 (#108G5)

>Seems like there must be more to the story. For example the autonomous operation is only "theoretical"?

One only has to look at some of the U.S. smaller market low-power tv signals to get an idea of what can go wrong. Some are really messed up, and even some of the better performing ones occasionally go down after a power outage or other disturbance and don't come back up unless someone calls the parent station to tell them to check it. Many operators can't see the output of their own transmitters and really don't know what is going on.
Many of the analog stations were rebroadcasting noisy signals from other other low-power stations or misaimed dishes. Some have undetected configuration problems like out of phase audio. (signal produced sound on a stereo tv, but it cancelled out on a mono set) If there is some overlap of coverage of low-power stations, there may still be some audience responses from an area with a sick site. I've seen one station that NEVER has had any audio, and the operator didn't fix it even after being told about it.

Simple things, like a strong wind gust (or sandstorm?) might knock the satellite dish out of alignment. A dish that's close-enough when set up in good weather might not always give adequate signal under other atmospheric conditions. High operating temperatures might contribute to r.f amp failure, or maybe the oscillator going out of lock. Maybe the box isn't quite weather-tight and some moisture gets in contributing to currents between circuit traces, or corrosion.
Old-school equipment would have used a crystal to set the desired transmit channel, but it's more likely there is a digital synthesizer (similar to what's in modern FM tuners) that makes it easy to change frequencies. While the added complexity adds flexibility, it also adds more failure modes. Who knows, a stray cosmic ray might cause the digital section to freeze up. A problem that could be cleared by a simple reset/reboot might persist if there's no one around to do it. If the solar power and battery voltage drops too low, will the equipment always go back to a controlled stable state after experiencing slow transitions through a below normal supply voltage range? Of course these sorts of potential problems apply to the satellite receiver too.

If the transmitter has a display, it's probably a design with a cpu in control of the frequency synthesizer, trim of output power, and monitoring of things like reflected power (an indication of how well the antenna is adjusted to transfer energy from the transmitter). Having a cpu generally lowers reliability, but a custom design might be set up to do intelligent things like adjust the operating hours and power level to make best use of the available power supply ability. I doubt that any custom development is being done.

Moderation

Time Reason Points Voter
2016-01-28 22:35 Interesting +1 hyper@pipedot.org

Junk Status

Marked as [Not Junk] by evilviper@pipedot.org on 2016-01-29 08:06