Experiment: Build Your Own Stream

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johnmoe1

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[size=+2]Quick Start[/size]
Go to: Scanner Click "Enable Audio". Select desired talkgroup(s). Enjoy.

[size=+2]Background[/size]
I've been experimenting with listening to ARMER for a while. I have mostly recorded and listened to the audio later. I decided it might be fun experiment with listening "live". This is my first attempt at listening live. It seems to be mostly working, so I thought I would share. I have tried it using Chrome, Safari and Firefox (on Mac OS X). I expect it will also work using those browsers on Windows. It seems to work on iOS (scrolling the talkgroup list is a little strange; try zooming out). It will not work with Internet Explorer.

[size=+2]ARMER Sites[/size]
I listen to 11 sites. When a talkgroup is heard on multiple sites, I average the signal hoping to get a clearer signal.
[size=+1]* Mostly Good Reception[/size]
Anoka, Dakota, Goodhue, Hennepin East, Minneapolis, Ramsey, Washington
[size=+1]* Often Not Great[/size]
Carver/Scott, City Center, Hennepin West, Rice

[size=+2]Talkgroup Choices[/size]
I didn't put a lot of effort into this. I was aiming largely for talkgroups that are likely to already be available to stream. I am sure I am missing a ton. If you would like to have talkgroup(s) added, leave a message. They are easy to add. (If the talkgroup is frequently carried only on say Hennepin West, I might not be interested. I also tried to skip talkgroups that I am not sure I receive all of.) If you want to suggest a better way to organize the list, I would be interested in that.

[size=+2]Overlapping[/size]
I think there are about three reasonable options for how to deal with multiple active talkgroups at the same time.

[size=+1]* One wins; others dropped.[/size]
I think this is what most scanners and stream do today. I might add this. Do I add some sort of priority?

[size=+1]* Play them all simultaneously.[/size]
I will probably add this as an option eventually. With a bunch of busy talkgroups, I think this would probably give me a headache. I am also not sure how I would show who is talking.

[size=+1]* Play them one after another.[/size]
This is what I do today. This means that if you select enough talkgroups, you will continually fall farther behind and never get caught up to the present. Don't select so many talkgroups.

[size=+2]Delay[/size]
Scanner: ~0 constant.

Stream: ~30 seconds (guessing) constant.

This: Variable. The audio is collected and sent when the person is DONE talking. This is not very noticeable for normal conversations where the average message is only a few seconds long. It is noticeable for things like fire dispatches which can end up like: tones; 45 second pause; 40 seconds of message. Of course the delay can get even longer if someone else is talking on some other talkgroup (see Overlapping).

Possibile Option: I could delay everything by XX seconds and then every transmission less than XX seconds would have a constant delay. Most ARMER talkgroups (or radios or whatever) seem to limit transmissions to about 59 seconds.

[size=+2]Equal Loudness[/size]
I currently don't implement anything to increase the volume of people who talk very softly. I should. My cat would also appreciate an option to reduce the volume for pager tones.

[size=+2]User Interface[/size]
It looks terrible. You can't yet bookmark a set of talkgroups or anything. It might be nice to allow clicking a talkgroup to switch to replay-recent mode.

[size=+2]Guarantees[/size]
None. I make NO guarantees that this will work or be available. It will stop if my power goes out, if my Internet goes out, if I reboot the computer and for many other reasons.
 

ofd8001

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Thank you for doing this work and providing this stream.

It works quite well on an iPhone.

Thanks again
 

JT-112

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Nice job!

This is *very* nice. The audio quality is near commercial-equipment quality. Certainly no issues with CPQSK demodulation!

A few comments - on the overlap, you're handling it perfectly now.

I've listened to multiple radios at one time, it's a major PITA. You lose many many transmissions when they're on top of each other. I personally wouldn't want one TG dropped either - which one to pick? By the way, just because scanners do this doesn't mean it's something to emulate.

I've been listening for more than an hour now, and two different incidents have occurred. My idea of which TG was more important that the others changed dramatically as time went on. With the transmissions being stacked up the way they are now, all I had to do was be patient and let the backlog of audio clear out, and just selectively listen for what I was interested in. I missed not a single transmission. I didn't mind the fact that I wound up being a few minutes behind real time, it's not an issue in reality for people listening casually.

I brought the backlog down by just de-selecting other TGs and it caught up fairly quickly.

The audio quality is quite nice; it does seem to vary a bit from TG to TG but nothing to be up arms about. P25 audio should generally be binary - either you get or you don't, so I'd be interested in learning more about the averaging that you're using. Ideally, you'd like to select the best audio based on BER but if the software you're using doesn't provide that then you won't be able to do that.

Some of the FD pages are extremely high quality - are you also bringing in the VHF channels? I note that some of the IDs for those pages are "--" and not the RID involved.

Regarding delay - looks like you've considered "hang time" where you package up the audio for a sequence of transmissions, I'd recommend that, as it would make listening to multiple talk groups much easier.

You might also consider holding the display for a bit longer than the audio. I don't always have time to look at the screen while the transmission is going on, or the transmission is so brief I don't see the screen in time.

Can you also explain the green circles? Two green circle seem to indicate all is working. I locked my iOS device and lost audio, when I unlocked it, one of the circles was red but then went back green and audio came back automatically.

This is good stuff!

How about adding the HCMC EMS dispatch channel?
 

johnmoe1

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And just now my power went out, so I expect that you will see a green dot and a red dot until I get everything rebooted.

Should be back.
Top green dot means your browser thinks it has a good connection to the web server at Amazon that is hosting the site.
The bottom green dot means you have received a message in the last 10 seconds from my computer running the radio (through the web server at Amazon).
 
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JT-112

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Actually didn't notice a thing....

Also saw you added HCMC, thanks for that!
 

johnmoe1

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HCMC Dispatch added (under Hennepin County).

No VHF. (I am using my one radio receiver tuned to ~856 MHz with a 10 MHz bandwidth.)

Averaging ... I am averaging at the level of deciding what value to assign to each symbol. Almost all of the software I am using was written by me. It can do anything as long as I am willing to write it.

Display holding would be nice. I will probably also add some sort of jump back (repeat) type feature.

The "--" radio id means that I have recorded a radio id of 0 for that transmission. There are basically two possible reasons for that. 1) A radio id of zero was sent. This seems to happen with some dispatch tones. 2) I missed the radio id. This generally happens with very short transmissions where I somehow miss the voice grant message (or there isn't one?) and there isn't time for an embedded link control message.

Hang time... I am not doing this at all right now. It would make listening less confusing.
 

stmills

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Very cool site- nice job- . I have to agree, the audio is great quality, and I really like being able to select what feeds I want to listen to.
 

MPSMP

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Question.. How did you get the tags to show what user/agency is transmitting? Example, it shows Anoka co dispatch calling a Coon Rapids car and when they respond it shows Coon Rapids.
 

johnmoe1

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Question.. How did you get the tags to show what user/agency is transmitting? Example, it shows Anoka co dispatch calling a Coon Rapids car and when they respond it shows Coon Rapids.

Too many hours of listening and creating a very large list of radio ids and descriptions:
https://github.com/johnmoe1/ARMERData

[The file is probably misleading large; there has been quite a bit of switching away from the Motorola Gold Elite consoles and I haven't gone through and removed all of those radio ids.]
 

wogggieee

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This is very cool. I'd be interested to know more behind the execution of this. How many of what radios? What software, something you wrote yourself?
 

ofd8001

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I've been spending quite a bit of time monitoring this feed on my iPhone and continue to be impressed. It brings back many fond memories of long ago when Minneapolis PD was on VHF high and I spent hours listening to them.

Now that I've grown up and moved away, I still like listening to them when technology such as this, allows.

Just out of curiosity, are their plans ton add the Interoperability TAC channels? I was listening yesterday to what sounded like a potentially major incident and one of the ME Tacs were used.

Also, to help me understand something: On the state patrol talkgroups, I hear what sounds like "KA" units. What are these? Also, sometimes I hear "SP" precede a unit number, which I presume is a state patrol unit. Sometimes I don't hear that. Is this just a case of some trooper use "SP" and some do not?
 

8VSB

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"K" units

"K" units are DNR enforcement personnel or "game wardens" they are dispatched by the patrol.
 

stmills

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Below are examples of unit calls on the MN State Patrol Talkgroups- I think I covered mosted but probably missed a few:
K- MN DNR Conservation Officers
"2510 cars". "10 cars" - any car on the "10"" beat
SP454- a specific State Trooper
Troop 7,8,9 - Helicoptor
Car# State Patrol Senior Leadership
2501, 2502 Etc- District Leadership
CVI - Commercial Vehical Inspector- 1612 - Etc
 
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