Check the various forum archives on this topic please
as I believe Carl, Bob, myself, and others had a rather
spirited debate on this very topic only a few years ago
when the 715 product was first released.
Both Bob and I independently did specific testing and
posted our results on the eHam forum product reviews.
http://www.eham.net/reviews/review/82963
http://www.eham.net/reviews/review/78012
Have a great weekend!
73 de Billy, AA4NU
-----Original Message-----
>From: Carl Moreschi <n4py3@earthlink.net>
>Sent: Mar 15, 2013 9:41 AM
>To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
>Subject: Re: [TenTec] Omni VII Speech Processor Question
>
>A DSP speech processor is not an RF clipper. In DSP you are working
>with signals that are all numbers. You can modify the numbers according
>to some clever algorithm and increase the average talk power. Then the
>numbers get converted back to an analog signal that represents the
>amplitude and frequency of the numbers.
>
>Even though it would seem that this scheme should provide the best
>results possible, the RF speech processors do a better job. In a
>classic RF speech processor, the audio signal is first converted to an
>RF signal. Then the RF signal is clipped. Then the RF signal is
>filtered and converted back to audio. The advantage of clipping at RF
>is the harmonics produced at RF are much higher in frequency and can be
>easily filtered out. When you clip at audio, the harmonics are still in
>the audio range and cannot be filtered out.
>
>Carl Moreschi N4PY
>121 Little Bell Dr.
>Hays, NC 28635
>www.n4py.com
>
>On 3/15/2013 10:25 AM, Rick - DJ0IP / NJ0IP wrote:
>> Gary, I disagree, it is not an AF clipper.
>> It may not do as good of a job of amplifying and clipping as the 715 does,
>> but then that's a question of design.
>> If it is operating in the DSP, it is RF, not AF.
>>
>> Bob says it operates in DSP. I am assuming he is correct.
>> The DSP frequency is too high to be AF.
>> It also means it won't have the harmonic distortion that AF clippers have.
>>
>> 73
>> Rick, DJ0IP
>>
>>
>>
>>
>> -----Original Message-----
>> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of GARY HUBER
>> Sent: Friday, March 15, 2013 2:29 PM
>> To: Discussion of Ten-Tec Equipment
>> Subject: Re: [TenTec] Omni VII Speech Processor Question
>>
>> I've kept the 715 to use with my OMNI-VII. I also have a FLEX-1500 as
>> sub-receiver of the OMNI-VII using the N4PY modification and DXLab Commander
>> to slave it. The FLEX-1500 has a panadapter mode with peak hold option
>> which I use to capture and compare the power distribution in the transmitted
>> envelope of the OMNI-VII.
>>
>> The TT-715 speech processer is of course a RF-clipper, external to the
>> radio. It may not sound pleasing, but it can increase the average power in
>> the transmitted (RF) envelope by six dB and get through QRM or poor
>> propagation.
>>
>> The internal speech processing of the OMNI-VII being an AF compressor cannot
>> increase the average power by that much, but it does help you get through.
>>
>> See http://www.sm5bsz.com/dynrange/dubus405/dubus405.htm for an unbiased
>> explanation.
>>
>> I will send png graphics of various microphones and processing methods used
>> with my OMNI-VII and captured with my FLEX-1500 in panadapter mode direct to
>> those requesting same.
>>
>> 73 ES DX,
>> Gary -- AB9M
>>
>> -----Original Message-----
>> From: d.e.warnick@comcast.net
>> Sent: Friday, March 15, 2013 6:37 AM
>> To: Discussion of Ten-Tec Equipment
>> Subject: Re: [TenTec] Omni VII Speech Processor Question
>>
>>
>>
>> I had the 715 with my Omni VI+'s and loved it. When I got the Omni VII, I
>> used the internal processor (only 10%) and I get so many unsolicited
>> comments on the audio during contests and while working DX, that I sold the
>> 715. I believe the internal processor is RF based, but either way, the other
>>
>> stations love the audio enough to comment on its quality.
>>
>> And all this from a guy who doesn't really like SSB, but much prefers CW.
>>
>> For me, TenTec does it all very well.
>>
>> 73
>>
>> Dave
>>
>> WA3F
>>
>>
>>
>> ----- Original Message -----
>>
>>
>> From: "Richards"<jruing@ameritech.net>
>> To: "Discussion of Ten-Tec Equipment"<tentec@contesting.com>
>> Sent: Friday, March 15, 2013 3:54:22 AM
>> Subject: Re: [TenTec] Omni VII Speech Processor Question
>>
>> Interesting -
>>
>> Stan at TenTec HQ says the Omni VII built-in
>> speech compressor uses "AF Based" compression.
>>
>> And... yet...
>>
>> Page 31 of my owner's manual states:
>>
>> "The speech processor used in the Omni VII is a
>> DSP generated RF compressor. ... RF Compression
>> raises the average output power... with a digitally
>> generated RF speech processor... we have the
>> advantage of calculating the RF envelope before
>> modulation is performed..."
>>
>> Page 38 Specifications says:
>>
>> "Speech Processor: RF compression, 0-9 adjustment."
>>
>>
>> So... perhaps one might understand how I came to wonder about this.
>> The phrases, "DSP generated RF compression" and "RF compression" do
>> not exactly sound like "AF compression" to me.
>>
>> ;-)
>>
>> Parenthetically... I paid my dues and purchased the Model 715 when it
>> first came out. I was just wondering if it was redundant, if the Omni
>> VII function was, in fact, RF-based at it sounded (to me, anyway) in the
>> owner's manual.
>>
>> THANKS AND HAPPY TRAILS.
>>
>> ----------------- JAMES - K8JHR ----------------------------
>>
>>
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