GPS Antenna
After 6 weeks as a snowbird down at Orange Beach, I returned home to EN52wx and found my outdoor GPS antenna had also gone south when I was gone. Thus, I am now temporary running the Kiwi on an indoor antenna.
Definitely, this is not as good as the outdoor one and at least on FST4W will create too much spread.
New I am looking for a new outdoor antenna. I am thinking about a marine one this time, but wonder if this is the way to go, or ?
Comments anyone?
Rolf K9DZT
these are known to work and are commonly on eBay
https://www.ebay.com/itm/225277478090
Greetings ya'll
After 6 weeks as a snowbird down at Orange Beach, I returned home to EN52wx and found my outdoor GPS antenna had also gone south when I was gone. Thus, I am now temporary running the Kiwi on an indoor antenna.
Definitely, this is not as good as the outdoor one and at least on FST4W will create too much spread.
New I am looking for a new outdoor antenna. I am thinking about a marine one this time, but wonder if this is the way to go, or ?
Comments anyone?
Rolf K9DZT
the spectral spread of your FST4W decodes are not influenced by the GPS correction in the Kiwi. The GPS will only correct the frequency offset from time to time. The contribution of the Kiwi to the reported spectral spread is a characteristic of the clock oscillator used in the Kiwi.
John DF4UE
I think that this is correct for the shorter FST4W modes such as
-120 which has sub-second symbols. The correction/aiding of the
Kiwi's GPS may only happen every 1 or 2 seconds, so the Kiwi's
crystal alone determines the spread within a symbol time. Values
on the order of 35 mHz seem typical of most Kiwi's although
(perhaps) we know of one that was very much worse.
For long modes, -600, -900, -1800 it is possible that the
on-board GPS-aiding might make a difference.
This is perhaps less of an issue since -900 and -1800 are possibly too long and too demanding for mid/upper HF use with propagation involving the ionosphere. I don't know if Kiwi GPS-aiding occurs frequently enough to make a difference for -300, or not.
Has anyone examined this?
Rolf,
the spectral spread of your FST4W decodes are not influenced by the GPS correction in the Kiwi. The GPS will only correct the frequency offset from time to time. The contribution of the Kiwi to the reported spectral spread is a characteristic of the clock oscillator used in the Kiwi.
John DF4UE
Rob discussed this with John Seamons last year and he added the possibilty in the admin page of the Kiwi to adapt the GPS correction to a specific WSPR or FST4W mode.
So correction always happens outside of the transmission cycle.
Not mentioned in the CHANGE_LOG, but for the WSPR/FST4W settings the ADC clock corrections occur in the 8-10 second window at the end of the cycle (mode dependent)
73
John
I remember Rob telling us later that it is not needed to handle the GPS signal this way.
Erwin,
I confess to not being fully up on this topic but I do believe
that GPS-aiding in the Kiwi when put into 'continuous' mode does
result in spreading that typically measures on the order of 35 mHz
on 20m. This has been what I've measured at any rate.
I'm unclear of the value of the other selections, modulos even-2/WSPR, 5,15 and 30 (FST4W). If and when I do run with only GPS-aiding I always select 'continuous'. I presume that the timing engine within the on-board GNSS module does not calculate and deliver timing information more often than every second, but I don't know this for sure.
Glenn
Doing it outside of the Rx cycle of the longer modes would mean that the drift during the Rx cycle is not influenced by the GPS. It only means that GPS based frequency corrections during a Rx cycle are not disrupting anything.
I remember Rob telling us later that it is not needed to handle the GPS signal this way.
Doing it outside of the Rx cycle of the longer modes would mean that the drift during the Rx cycle is not influenced by the GPS. It only means that GPS based frequency corrections during a Rx cycle are not disrupting anything.
I remember Rob telling us later that it is not needed to handle the GPS signal this way.
