[amsat-bb] Station decisions re. upcoming Geosync bird
nss at mwt.net
Thu Mar 24 12:46:14 UTC 2016
That isn't too bad.
It would be a killer when running CW and monitoring like a sidetone tho!
he he he.
The Original Rolling Ball Clock
On 3/24/2016 7:35 AM, Paul Stoetzer wrote:
> 240-280 ms
> Paul, N8HM
> On Thu, Mar 24, 2016 at 8:31 AM, Joe <nss at mwt.net> wrote:
>> Full Duplex on a Geo Bird,,,,?
>> What is the delay lag time on such a distance?
>> Joe WB9SBD
>> The Original Rolling Ball Clock
>> Idle Tyme
>> On 3/23/2016 11:17 PM, John Toscano wrote:
>>> Details on the satellite are still quite sensitive, but details on ground
>>> station requirements are much more readily discussed due to the lack of
>>> ITAR restrictions there.
>>> One approach to the ground station would be to add a 5G and a 10G
>>> transverter to your existing radios, using them for IF radios. Though many
>>> 5G and 10G transverters use a 144 MHz IF, some are available with a 432
>>> IF. Getting one of the two transverters with a 432 MHz IF and one with a
>>> 144 MHz IF would probably facilitate full-duplex operation, unless you
>>> two 144 MHz IF radios available.
>>> This sort of approach might be preferred by an operator who plans to add
>>> those two bands to BOTH terrestrial and satellite operation. But if you
>>> were adding these two bands for satellite use only, there is significant
>>> opportunity for financial savings. You only need a 5G transmitting
>>> converter and a 10G receiving converter. On the receiving end, a modest
>>> satellite dish and an inexpensive LNBF designed for for satellite TV will
>>> convert the satellite downlink to a signal somewhere near 700 MHz, which
>>> easily within the RF range of many software-defined radios. The ground
>>> station team has been hoping that an under-$20 satellite TV PLL-LNBF
>>> coupled with an inexpensive RTL-SDR dongle MIGHT suffice for the heart of
>>> the 10G receiver. For the uplink, it is possible that a $300-ish HackRF
>>> SDR (which can transmit at up to 6 GHz), coupled with appropriate
>>> and a suitable power amplifier might form the heart of an inexpensive 5G
>>> transmitter. The ground station team is looking at other, more expensive
>>> solutions, as well, and we can't yet promise that the rock-bottom-price
>>> solutions will work until they have been well-tested.
>>> In any event, digital modes are going to be the order of the day, so if
>>> are using a pair of all-mode radios as IF's, they will need to support a
>>> digital interface to a computer. That's one of the reasons why we are so
>>> excited about the possibilities of SDR to get us from RF to digital data
>>> and back at affordable prices.
>>> \I hope that helps at least a little bit.
>>> John Toscano, W0JT/5
>>> On Wed, Mar 23, 2016 at 7:44 PM, Peter Klein <pklein at threshinc.com> wrote:
>>>> I've been casually following the discussion of the upcoming
>>>> satellite. I currently have a Mode B , J and A analog setup that I've
>>>> on Oscar 10 and 13, and on some LEOs. This includes crossed Yagis on 2m
>>>> 70cm, and an all-mode radio for those bands. LEOs and flying mailboxes
>>>> longer interest me, so in recent years that setup has only been used for
>>>> occasional terrestrial VHF SSB/CW, plus local repeater activity.
>>>> I will need to make some decisions on my general station setup soon.
>>>> Antenna space is limited, and I want to take the possibility of the
>>>> bird into consideration. From what I've read and seen on video, the
>>>> uplinks and downlinks to the satellite will be microwave. The satellite
>>>> track will make a figure-8 pattern in the sky, but I don't know how large
>>>> that pattern will be at my location. My 144 and 440 MHz antennas will not
>>>> be compatible with the new bird. But will the 144/440 radios be useful,
>>>> perhaps as an IF after the digital gymnastics happen in a converter?
>>>> So, my questions:
>>>> - Are any "dummy" Keplarian elements available for the geosynch bird's
>>>> planned (or likely) orbit? That would let me do some "what-iffing."
>>>> - If the above are not available, could someone tell me the approximate
>>>> range of azimuth and elevation I might expect from CN87 (Seattle area)?
>>>> - What is the physical size of the required dishes?
>>>> - Will the radio for the new bird be self-contained, or require another
>>>> radio as an IF? If the latter, what frequency band or bands are being
>>>> contemplated for the IF?
>>>> If I've asked things that are too sensitive to discuss right now, let me
>>>> know and I'll shut up. :-)
>>>> --Peter, KD7MW
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