Batboard

I saw a post that mentioned that the new Uniden scanners cannot monitor VSLEP. Is this true? Are there any advantages to using IMBE as compared to VSLEP?
Thanks,
Scott

RESCUE161 wrote:I saw a post that mentioned that the new Uniden scanners cannot monitor VSLEP. Is this true? Are there any advantages to using IMBE as compared to VSLEP?
Thanks,
Scott

Hey Scott,
Thanks for the reply on the other subject.

I posted that VSLEP couldn't be monitored.
I had this bigtime scanner buff boasting how his 730+ dollar APCO scanner "DOES IT ALL".
so, I gave him one of my astro simplex channels and he heard nothing but the digital carrier.

This could have been operator failure on his part but because VSLEP is not APCO the scanner couldn't decode this flavor of astro! (I think I'm still an astro newbee if measured by the others out here!)

RESCUE161 wrote:I saw a post that mentioned that the new Uniden scanners cannot monitor VSLEP. Is this true? Are there any advantages to using IMBE as compared to VSLEP?
Thanks,
Scott

VSELP is noisy and old. It is/was Motorola's original "ASTRO" product. It's a Motorola proprietary format used by few agencies/companies, namely The City of Cleveland, Nextel, and Southernlinc, although the latter 2 are even worse as they're compressed.

At any rate, few agencies use VSELP as IMBE is the 'open' protocol for APCO-25 compliance.

-Josh

VSELP is not necessarily better, or worse, than IMBE. The point is that these involve two different VOCODERs. IMBE won out as the Comman Air Interface (CAI) standard in connection with P25. Just like VHS vs. BETA, die hards still argue the merits of each, but in the end, it's the industry standard that always wins out. That's why I feel sorry for any agency that got suckered into VSELP----it's going to cost them a lot of money to become P25 compliant!

Larry

VSELP really doesn't sound any different than IMBE. In fact, if I recall, Nextel is based on the VSELP vocoder.... so it works just fine.

VSELP does somewhat "sound" different, but the main thing is it's not as robust as IMBE. I have some notes & comparison graphs somewhere, showing the difference in audio quality vs. signal strength for both. IMBE is clearly superior over a wider range, simply because it's a better A/D method than the linear prediction model on which VSELP is based. Thus, it was chosen as the APCO-25 standard digital protocol over VSELP. The reason your buddy's scanner couldn't decode it...scanner manufacturers aren't putting any effort into developing a product to scan a dead-end technology.

Todd