[HCARC] Fw: FW: SYSTEM FUSION NET

Thu Nov 27 21:27:51 EST 2014

That's exactly right, Gary.

Let me take you all back about 35 years.  Has anyone ever heard of 
Narrow Band Voice Modulation (NVBM)?  Let me quote from "It Seems to 
US..." in the Sept 1978 QST.  This is an editorial by Dick Baldwin, 
W1RU, General Manager of the ARRL .  In those days the General manager 
was the same as today's Executive Vice President or Chief Executive 
Officer or whatever K1ZZ's latest title is.  The editorial is titled 
"Dawn of an Era"  It starts with "Last December we were privileged to 
share with League members the first published information on a 
technological breakthrough which promises to revolutionize voice 
communications: narrow band  voice modulation (nbvm).  Nvbm is a 
technique for compressing speech frequencies so that only about half the 
normal bandwidth is used."  It says later in the editorial, "Nbvm has 
important applications to other services as well.  An FCC study group 
has conducted tests of the system for Land Mobile applications and has 
tentatively concluded that a considerable saving of spectrum could be 
accomplished by replacing the present fm mobile equipment with 
single-sideband gear using nbvm."   The editorial concludes with "We're 
proud that through QST, League members will be able to be at the 
forefront of this important development."

Not only didn't it become a popular amateur mode, it hasn't even been 
utilized by the LMR community.  I don't believe there were very many if 
any NBVM radios manufactured by anyone for any use.  It just wasn't 
worth the trouble and just didn't work that well.  I believe the 
commercial versions of digital radio such as P25, TETRA and perhaps DMR 
will be used in the LMR bands.  One of the drivers in the Public Safety 
bands is the need for secure (encrypted) voice. This pretty much 
requires digital techniques.  But encryption is not legal in the amateur 
bands so this isn't a player for us.  I don't know how useful or 
practical digital voice will be for hams and I sure would take a wait 
and see attitude until it proves itself to be practical, inexpensive and 
popular.

My last e-mail, I talked about the need for linear amplifiers.  The 
digital modulation schemes do use multiple carriers.  System Fusion 
claims to use C4FM which has 4 carriers.  Typically to linearize an FM 
amplifier, you have to reduce the gain by 6 - 10 dB.  Now your 10 W FM 
transmitter is a 1 - 2.5 W transmitter for C4FM.  That is quite a hit.

Kerry

On 11/26/2014 11:27 PM, Gary J - N5BAA wrote:
>
>
> -----Original Message----- From: Gary J - N5BAA
> Sent: Wednesday, November 26, 2014 11:26 PM
> To: Kerry Sandstrom
> Subject: Re: [HCARC] FW: SYSTEM FUSION NET
>
> Do you mean Kerry that "IF THEY BUILD IT - THEY (WE) DON'T HAVE TO 
> COME"??
> Heck, Bill Tynan recently put up a 900 mhz repeater at his cost and 
> I'd bet
> there are very few that have started using that one.  I might, but every
> Alinco 900 mhz handheld I find costs me well over $200 (closer to 300)
> dollars.  I then can make a choice to spend the $$$ on coax or 
> antennas for
> HF and sorry Bill - 900 mhz loses out.  I have asked on here if there 
> is a
> less cost 900 mhz radio out there, but to date haven't heard one 
> suggestion.
> The last thing I need to do would be buy a Fusion radio to have it sit 
> idle
> too.
>
> BTW, for the new guys - VERTEX Standard makes Yaesu.
>
> Gary J
> N5BAA
>
> -----Original Message----- From: Kerry Sandstrom
> Sent: Wednesday, November 26, 2014 9:11 PM
> To: Gary J - N5BAA
> Subject: Re: [HCARC] FW: SYSTEM FUSION NET
>
> Gary et al,
>
> I think Gary has made a good comparison.  This is kind of like the Beta
> vs. VHS VCR battles.  Many would suggest that that battle was one not by
> the best technical system but the one that was least expensive. There
> are still people who are trying to keep Beta alive.  Unfortunately both
> seem to have lost out to DVD and then Blu-ray.  There are some
> differences however.  We don't have 2 competing systems - we have at
> least 5.  The three additional ones are TETRA, the European LMR digital
> system, P25 the US LMR digital system and DMR, another European LMR
> system.  Because of FCC rules on bandwidth in the LMR bands, I expect
> every public safety 2-way radio in North America will be a P25 digital
> radio.  Same thing is happening in Europe except it will be TETRA.  Why
> do hams want to create a different incompatible system.
>
> All the systems claim compatibility with analog FM but none claim any
> compatibility with other digital systems.  As a minimum, we need to wait
> to see which system is the winner.  Cost will eventually be determined
> by economy of scale.  Companies selling P25 radios include Motorola,
> Codan, Harris, Midland and the commercial parts of ICOM, Kenwood and
> Vertex Standard.
>
> I don't have any idea of how the FCC will eventually react to these
> systems in the ham bands.  Already, I believe the 2 meter band can't be
> used for remote control.  I'm not sure what the restrictions are or may
> be applied to 9600 baud data.
>
> Some of the digital systems require linear amplifiers.  I don't know if
> all do.  TETRA is one that I believe does require linear amps. Yes,
> digital signals do and will cause interference.  Turning the squelch up
> merely ensures that you won't hear weak FM analog signals that are
> receiving digital interference.  That means some of the weaker analog FM
> signals will not be workable.  Typical narrowband digital signals
> require a higher S/N than analog FM, that's why the coverage of the
> digital signals is not as good as the analog signals.  Error correction,
> FEC, and coding help with pulse type interference but do little for
> continuous interference. Unfortunately the response of most digital
> systems to interference is to retransmit the messages that can't be
> decoded probably.  This doesn't exactly help the interference situation.
>
> I'm not sure what compatibility really means in the case of repeaters.
> What I think it means is that a digital signal will be repeated as a
> digital signal and an analog signal will be repeated as an analog
> signal.  I don't think a digital user will be able to talk to an analog
> user.  I may be wrong, but that is how I interpreted compatibility.
>
> So where does that leave us?  Digital and analog on the same repeater
> simultaneously is not realistic.  When both are present at the same
> level, I think digital will suffer more than analog. Digital coverage at
> the same power levels will be less than analog. I would wait until there
> is a real standard with real support. Right now, I don't think either
> Dstar or Fusion will be that standard.  Finally, yes there are a lot of
> fun things you can do with data, but I don't know how many of them are
> legal, especially in the 2 meter band.
>
> No, I'm not a fan of digital systems on the ham bands.
>
> Kerry
>
>
>
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