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OpenSky Scanner???

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mikey60

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If I understand correctly, OpenSky uses the TDMA format so, looks like there is a scanner out now for it.

Maybe????

YEEEEHAAAA!!!
No such luck I'm affraid. I wish we did have something that could monitor OpenSky. It would be nice to hear my city's PD/FD again.

Mike
 

GTO_04

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they can't make OpenSky work more or less a scanner to monitor that type of system.
Ditto that. Not much point in making a scanner for a system that very few public safety agencies are using, or should I say attempting to use.

Open Sky is so "secure" even the system users can't monitor it!

GTO_04
 

n7jei

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davidzimmerman said:
they can't make OpenSky work more or less a scanner to monitor that type of system.
LOL!
 

n7jei

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OHI063 said:
OpenSky systems do not use a control channel. Like ProVoice Open Sky cannot be monitored by any scanner, past or future.

"From the Wiki"
Also from the wiki; pro-voice can be monitored with a provoice radio or with the setup described in the wiki.
 

n7jei

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OHI063 said:
OpenSky systems do not use a control channel. Like ProVoice Open Sky cannot be monitored by any scanner, past or future.

"From the Wiki"
Also from the wiki; pro-voice can be monitored with a provoice radio or with the setup described in the wiki.
 

mdickerson17

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I read somewhere in the forums that someone created a decoder via Linux software for ProVoice unfortunately I'm unable to find it at the moment. Wondering if he could make a OpenSky decoder if its even possible........
 

machinegeek

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Status of OpenSky monitoring efforts

The main reason we won't seen OpenSky capable scanners sold anytime soon is due to licensing and intellectual property issues surrounding DVSI's AMBE vocoder.

I have conducted considerable research on this topic as I reside in Pennsylvania. I believe the only possibilities for dedicated hobbyists are as follows:

1. Examine the free open source Linux programs known as DSD and its companion MBELIB. When installed on your Linux computer and fed audio into the soundcard from your radio discriminator tap (NOT the headphone jack), these programs can do some pretty amazing things like demodulate APCO25 and many other digital protocols. They will also do TDMA 2 slot decoding (remember, OpenSky is TDMA 4 slot); when you pipe OpenSky signals from your radio through this program it actually appears to recognize packets and you occasionally hear muffled mono-syllables from your computer's speaker! So it appears that it we knew enough about how to mod these free programs (their author is anonymous) we might be able to make some progress. These programs are written in the "C" programming language.

2. Consider the costly but promising alternative of buying a USRP software defined radio from Ettus Co. These radios cover the necessary frequencies (with the appropriate daughtercard installed) and when used with the powerful companion free software known as GNU Radio it provides unlimited possibilities. I do not believe I am exaggerating when I say that if you buy a USRP and the 800 MHz capable daughtercard and get it hooked up to a computer running GNU Radio, you will have all the necessary components to make your own OpenSky monitor. However, this approach requires a great investment in learning digital signal processing on your part. If anyone is seriously interested in pursuing this course, let me know.

Some interesting info on this system in PA can be found at PENNSYLVANIA STATE POLICE RADIO IN WESTMORELAND COUNTY, PA

You can also sometimes find interesting surplus radio equipment being sold on Ebay. Just search Opensky.
 

bfperez

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We need an open sky scanner. Middlesex Count Nj is making the switch
If LV and the state of PA are any indication, a lot of intercepted traffic would consist of "We're here at the corner of da-da-da-da-da-da-da" followed by other party saying "Could you repeat that, your radio broke up?"
 

kc8cwp

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opensky

Since Opensky uses the same Audio Codec as most digital cell phones, the radios also have the range of most cell phones which is not very good without a tower every couple of miles. I know oakland county here in Michigan has made the switch. I heard that they ended up with 3x the transmitter sites as orig budget for. Also same deal with the PA state police.
 

lep

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This observation doesn't sound right to me. My background as a professional radio engineer doesn't lead me to connect the audio codec with the range of RF. Apples and oranges. Depends on the power (cell phones are limited to miliwatts), frequency, antennas an zillion things besides the way the audio is encoded. Since you display the 'amateur radio' badge I would think you would agree with my observations.
 

bfperez

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The only thing I could think of would be that the low level bit/frame encoding scheme OR the higher level codec/vocoder were less error tolerant than other encoding scheme. But, that would be a problem regardless of band, xDMA, etc.

If the things I've read are true, the vocoder/codec is the same AMBE used by satellite phones and D-Star.

Sat phones are rumored to be quite clear and reliable when you have a satellite. I just ordered an Inmarsat phone, so I'll get to find how true this is Friday. I don't read of D-Star uses having anything remotely close to the issues I've heard myself and read about with OpenSky.

If I had to throw out a random, uninformed guess, I would point at the underlying CDPD encoding as the more likely culprit. Without knowing the guts of it, it wouldn't surprise me that a packet-data centric 'protocol' isn't cut out for the rigors of voice data.

Slightly along the lines of how a fast controller based wifi network isn't necessarily good for voice. Roaming issues between APs may not be noticed at all by data clients that have buffering and transparent (to the user) timeouts whereas voice and video conference clients will immediately notice drops.

With that in mind, it wouldn't surprise me to hear that OpenSky does OK for data. But, I can't imagine it's any faster than the data speeds available on a decently constructed P25, SmartNet/Zone, EDACS, etc. system.
 

GTR8000

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With that in mind, it wouldn't surprise me to hear that OpenSky does OK for data. But, I can't imagine it's any faster than the data speeds available on a decently constructed P25, SmartNet/Zone, EDACS, etc. system.
OpenSky uses 25 kHz wide channels vs 12.5 kHz wide for P25. 19200 bps vs 9600 bps. More bandwidth = faster data.

Likewise that has a relation to the voice channels. 4-slot TDMA for OpenSky in a 25 kHz channel vs 2-slot TDMA for P25 in a 12.5 kHz channel.
 

jim202

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What it all boils down to is that your all forgetting that the system was originally designed for data. Then some brain fart at MA-COM came up with the hair brained idea that it could be used for voice as well. We all know the great sales job done on the state of PA and just how well the system has worked for the state police there.

I think Harris would be glad when all the Open Sky systems go by the way side and get turned into a P25 operation.
 

bfperez

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OpenSky uses 25 kHz wide channels vs 12.5 kHz wide for P25. 19200 bps vs 9600 bps. More bandwidth = faster data.

Likewise that has a relation to the voice channels. 4-slot TDMA for OpenSky in a 25 kHz channel vs 2-slot TDMA for P25 in a 12.5 kHz channel.
True, but since they're breaking it into 4 slots, that speed edge is gone unless they're actually using all 4 slots for the same data stream (which would seem to defeat the purpose of mandating 6.25k equivalency in the 700 mhz band and 12.5k in the others). I wonder if they would be allowed to use more than one slot as long as those slots weren't being requested by any other voice/data stream.
 
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