[Elecraft] Fw: [Pskten] PSK Signals

[Jim's mail]

----- Original Message ----- 
From: "Jeff Steinkamp" <n7yg at n7yg.net>
To: "Jim's mail" <jamesgood at dfwonline.net>
Sent: Wednesday, December 19, 2007 1:44 AM
Subject: Re: [Pskten] PSK Signals


> No Problem. forward away.  I als0 have a few discussions on my web site 
> about properly setting your transmiter and a discussion about IMD. 
> http://www.n7yg.net
> 
> Jeff N7YG
> 
> ----- Original Message ----- 
> From: "Jim's mail" <jamesgood at dfwonline.net>
> To: "Jeff Steinkamp" <n7yg at n7yg.net>
> Sent: Tuesday, December 18, 2007 15:21
> Subject: Re: [Pskten] PSK Signals
> 
> 
>> Jeff,
>>
>> This information sound really good.  There is currently a discussion 
>> on
>> another reflector I read on the topic of PSK and some of the settings 
>> that
>> should be used for better signals.  Would you mind if I forwarded your
>> message to that group?
>>
>> 73,
>> Jim Good KD5VXH
>>
>>
>> ----- Original Message ----- 
>> From: "Jeff Steinkamp" <n7yg at n7yg.net>
>> To: "PSK TenMeters" <pskten at web1.nwlaweb.net>; "PropNet Online"
>> <PropNET-Online at yahoogroups.com>
>> Sent: Tuesday, December 18, 2007 2:44 PM
>> Subject: [Pskten] PSK Signals
>>
>>
>>> In the few days I've had the 30 meter antenna up, I have been able to
>>> spend some time watching the capture of signals in PropnetPSK (PNP). 
>>> There
>>> has been some discussion in the past about PNP not acquiring a signal 
>>> that
>>> was quite strong.  This discussion will also apply to YGPSK and just 
>>> about
>>> every other PSK decoder that uses the PSKCORE.DLL as the Decoding 
>>> element.
>>>
>>>
>>>
>>> PNP and the PSKCORE.DLL are quite finicky on signal quality and over 
>>> the
>>> past few days I have observed a number of really terrible signals, 
>>> either
>>> because they are completely overdriven or due to atmospheric 
>>> conditions.
>>>
>>>
>>>
>>> If you look at a good PSK signal in the spectrum display instead of 
>>> the
>>> waterfall and spread the display out, you will notice that a good PSK
>>> signal has two signal peaks, approximately 31 Hz apart with a small 
>>> valley
>>> in the center.  A good signal lock-on will occur when the frequency 
>>> line
>>> is between these two signal peaks.  Any third order harmonic 
>>> distortion
>>> will be reduced by at least 60db.
>>>
>>>
>>>
>>> If the signal is overdriven, these third order products will be above 
>>> the
>>> 60 db attenuation and this is where problem can start.  If you look 
>>> very
>>> closely at an overdriven signal, you will see a mirror of the signal 
>>> in
>>> the third order distortion product on either side of the main signal.
>>> There will be 2 smaller peaks along with a valley.   If this portion 
>>> of
>>> the PSK signal is above the ambient noise floor, then the weak signal
>>> properties of PSK will lock on to this signal and start decoding 
>>> because
>>> it thinks it is a qualified PSK signal.  Depending on the quality of 
>>> the
>>> signal, it may or may not produce intelligence.
>>>
>>>
>>>
>>> This is why it is imperative that we make sure our transmitters are
>>> correctly adjusted for a good quality signal; rig power at something 
>>> less
>>> than the 100% duty cycle rating of the radio and absolutely no ALC 
>>> showing
>>> on the meter.  The last test will be to have someone locally have a 
>>> listen
>>> to the signal for quality.  There are a couple of commercial 'PSK 
>>> Meters'
>>> on the marker that will actually sample your transmitted signal and
>>> automatically adjust the sound card gain to keep you signal clean and
>>> pure.  I do not have one of these and therefore do not have any first 
>>> hand
>>> knowledge of these devices, but from the reports I have read, this 
>>> might
>>> be a very good addition to the shack for PSK or other sound card 
>>> digital
>>> modes.
>>>
>>>
>>>
>>>
>>>
>>> Jeff Steinkamp - N7YG
>>> Tucson, AZ
>>> SCUD Missile Coordinates
>>> N32-13-55.01 W110-50-51.91
>>> http://n7yg.net
>>> http://home.earthlink.net/~jksteinkamp
>>> Linux User #420428
>>> Skype : jeff_steinkamp
>>> Yahoo Messenger: n7yg
>>> _______________________________________________________
>>>
>>> 'I'm not the one that misplaced the Deltivid asteroid belt!' - Q
>>>
>>>
>>> _______________________________________________
>>> Pskten mailing list
>>> Pskten at web1.nwlaweb.net
>>> http://www.nwlaweb.net/mailman/listinfo/pskten
>>>
>>>
>>
>>
>> 
> 
> 
> 
>