[Allstar Digital] MD-380 Digital Timing Issue

Fri Dec 18 11:17:19 EST 2015

Ya I didn't want it to be a crap on the md-380. I thought Mike provided
some solid evidence on the radio. Doesn't mean it will stop me from owning
one.

N1XBM
Apparare Scientor
Paratus Communicare
Allstar Node # 27086, 41540, 41812, 42086, 42658

On Dec 18, 2015 11:10 AM, "Steve Zingman" <szingman at msgstor.com> wrote:

> I've heard the anecdotal evidence from West Palm Beach. I know the guys
> involved but I have not talked to them directly about the issue. The
> empirical data Mike is reprinting does look compelling. Jerry from CSI says
> he has also seen it on real test equipment. I have not seen it happen here,
> and I wish I had the equipment. I mostly listen just to my MD-380 at the
> work QTH, so I'm not too worried. Keep you eye on the front panel of your
> repeater while you setting up.
>
> Steve
>
> On 12/18/2015 10:47 AM, Robert Newberry wrote:
>
> Has anyone else seen this? I am forwarding it from another list. I'm not
> doing this to trash the md-380, it's technical and I thought the list might
> want to see it.
>
> N1XBM
> Apparare Scientor
> Paratus Communicare
> Allstar Node # 27086, 41540, 41812, 42086, 42658
>
> ---------- Forwarded message ----------
> From: "Mike N07RF no7rf at trbo.org [mototrbousa]" <
> mototrbousa at yahoogroups.com>
> Date: Dec 17, 2015 8:29 PM
> Subject: [MTUSA] Fwd: [pnw-dmr] Re: Tytera MD-380 Digital Timing Issue
> To: "mototrbousa" <mototrbousa at yahoogroups.com>
> Cc:
>
>
> I am forwarding this information as it is near first person and involves
> Aeroflex actually taking a look at the problems that we have been hearing
> with hams using the MD-380.  While the 380 users may not appreciate the
> issues, those who do hear them, should.
>
> I've neutered the attribution only as I don't have permission to forward
> the post.
>
> At this point, I'd caution folks to consider looking at other DMR radios,
> if not for their first DMR radio, then for their move up with subsequent
> purchases.  If a MotoTRBO radio is not on your RADAR, then the CS-750 has a
> great value to cost ratio and is DCI's recommended alternative if cost
> thrumps compatibility.
>
> -- Mike, NO7RF, Mazama Washington, no7rf at trbo.org
> <no7rf at trbo.org?subject=Reply+to+my+.sig>, www.trbo.org
>
>
> == == == == == == Forwarded message == == == == == ==
> From : <pnw-dmr at yahoogroups.com>
> Date : Thu, 17 Dec 2015 17:14:59 -0800
> Subject : [pnw-dmr] Re: Tytera MD-380 Digital Timing Issue
> == == == == == == Forwarded message == == == == == ==
>
>
>
> Here is another Tytera MD-380 observation.
>
> (In) December, I attended a digital radio service presentation by the
> well-known service monitor company Cobham/Aeroflex.  I brought my 450 MHz
> MD-380 along.
>
> After the presentation, I asked Mike Fortna of Aeroflex to take a look at
> the infamous MD-380.  He said Tytera had contacted them about developing an
> Autotest routine for Tytera products, so Mike was interested in seeing the
> Tytera MD-380's alignment.
>
> Testing was done on 441 MHz Simplex and again on TS1 on the Gunnysack pair
> with the Cobham/Aeroflex 8800S Digital Radio Test Set.  The 4FSK modulation
> was perfect.  Mike had just been explaining that most problems with
> alignment are revealed on the 4FSK display, but the Tytera was perfect.  I
> asked him to look at the energy in each timeslot.  I think this display is
> called the power profile.  The graphic showed timeslot 1 and 2
> simultaneously.
>
> What was observed was a non-standard rise time when keying the
> transmitter.  The power in timeslot 1 came up about half of maximum, hung
> there for a few uS, then went to full power.  It was not a nice rounded
> envelope.  It was a stair step.  No overshoot was observed.  Other than the
> "stutter" in reaching full output, the waveform was mostly normal.  The
> abnormal condition was likely caused by the "stutter" in rise time.  This
> abnormal condition is RF energy "spilling over" into timeslot 2 in this
> case.  It seemed to appear in timeslot 2 for the same duration as the
> stutter in the timeslot 1 rise time.
>
> Mike Fortna of Aeroflex found it interesting enough to take a screen
> shot.  He stated it was a better example of a DMR power profile alignment
> problem than what he was currently using.
>
> The same waveform anomaly occurred on Simplex and Duplex.  Rapid keying,
> de-keying and keying again made no difference in the waveform.  I have read
> that transmitting on both timeslots simultaneously was a "feature."  This
> doesn't seem to be true.
>
> I didn't have time to test on timeslot 2.  Testing was rushed because
> everyone knew that Seattle traffic was building!
>
> Further, more comprehensive testing is required with a greater pool of
> radios. It would be interesting to test some high-band models as well.
> Does anyone have an IFR3920 or 8800S with the DMR option?
>
> This only meant to be a verbal description of the graphical representation
> of an anomaly in my particular MD-380's timeslot power profi le.  Your
> mileage may vary, as they say.
>
> -- Mike, NO7RF, Mazama Washington, no7rf at trbo.org
> <no7rf at trbo.org?subject=Reply%20to%20my%20.sig>, www.trbo.org
> __._,_.___
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