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Thread: Audio Sample: Motorola ASTRO VSELP

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    Cool Audio Sample: Motorola ASTRO VSELP

    Ever wonder what Motorola ASTRO VSELP (Vector-Sum-Excited-Linear-Prediction) actually sounds like, as heard by another ASTRO VSELP radio? I can't say I've heard any other VSELP samples on the net before.

    I flashed up an ASTRO Saber III and XTS3000 Model III with the following firmware:

    Host: AP_R03.32.00
    DSP: N05.00.18

    I attached a Motorola Windport speakermic with a 3.5mm audio jack (output), to the XTS3000, wired directly to my sound card. I set the output level on the XTS3000 as best I could, so clipping was not occurring.

    Attached is a MP3 file of the audio testing.

    You know what? I think VSELP actually sounds better than IMBE, in the sense the vocoder doesn't seem to have such a narrow frequency-response on the input of the vocoder. What I mean by that, is IMBE tends to distort audio which doesn't fall into the range of human speech.

    VSELP sounds natural -- almost like analog.

    And I believe newer versions of VSELP firmware actually supported AGC, so it might even sound better than this test. If I'm able to get newer VSELP firmware (should have shortly) I'll post another test with AGC-processed VSELP audio.

    Also, the VSELP air-interface also sounds slightly different than what CAI (P25 modulation) sounds like. I didn't tape it on analog to compare, but there's definitely a difference. I know VSELP has a different sampling rate (and packet structure) so perhaps that has something to do with it.
    Attached Files Attached Files


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    Mars,

    Can you post the XTS3000 s-rec?

    Sure would save a lot of headaches on this end
    Last edited by Integrator; Jun 04, 2012 at 10:39 AM. Reason: typo

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    Believe it or not, I used the CAI codeplugs for the test. I didn't have to change out anything in the s-records.

    But if you want to create a legit VSELP codeplug, all you should have to do is drop CAI from the flashcode. Just remove 1xxxxx-xxxxxx-x and the corresponding option in the FDB.

    I will edit the s-record and post one up in the coming days. Do not have time this morning.

    Cheers

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    Yea that IS surprisingly nice audio. It doesn't have that watery unstable sound that IMBE has. It's almost like analog.

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    I was told years ago in Quantar school when we were discussing IMBE vs VSELP that the one of the main reasons APCO went with IMBE was because it worked better with high speed moving objects (squad cars). And that if it had not been for that they probably would have went with VSELP. Now this was coming from a Motorola instructor mind you so its probably a little biased but it makes you wonder how good VSELP would have sounded if they had kept developing it instead of switching to IMBE...

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    If only VSELP supported AES. VSELP sounds closer to analog IMHO

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    Yeah...this particular host version I'm using doesn't even support DES-OFB. It comes up as "UNKNOWN-X" for that algo. Does show DES-XL however...

    I'm waiting for the latest VSELP Host/DSP package. Will do the tests again.

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    I heard early vselp and it sounded horrible.

    The police department bought it for their Astro Smartzone system with the hope that they could cut down on iden costs.

    The officers using it preferred to stick with iden and it was rarely used.
    Cyrus

    Bubbles: I'd like to see that Red Blue Green c***sucker put one of those together, duct-tapin' it.

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    I was able to update to the latest VSELP firmware today. My test radios are now running:

    Host: AP_R04.10.00
    DSP: N05.01.07 (Also have the "I" build, which I'll post later in the download area)

    Guess what? No AGC support -- even with this final VSELP version. That sucks.

    I'll post audio samples later this evening. Doubt there's much of a difference, but?

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    Damn that sounds good!

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    Curious - Can you encode DTMF from the keypad on the VSELP radios?

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    That sounds pretty good, shame they chose IMBE which sounds like garbage compared to ProVoice, TRBO and just about any other digital mode.

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    Quote Originally Posted by Durchschnitt View Post
    That sounds pretty good, shame they chose IMBE which sounds like garbage compared to ProVoice, TRBO and just about any other digital mode.
    Provoice uses IMBE, too

    :P

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    Quote Originally Posted by d119 View Post
    Curious - Can you encode DTMF from the keypad on the VSELP radios?
    Test radios were flashed back to IMBE. There was no difference in audio quality (perhaps only slight?).

    When I was keyed in VSELP mode, the "hot keypad" did not send any DTMFs out.

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    Does ProVoice handle IMBE differently? I've tested a ProVoice Jaguar side by side an XTS5000 and found the Jag to have far superior audio.