Messages

166

Equipment / Re: Copper Clad Steel

« on: April 29, 2020, 1225 UTC »

More from Duffy.  One ham bought RG6 that started to see performance drop offs below 85 MHz.

https://owenduffy.net/blog/?p=17599

167

General Radio Discussion / Re: U.S. Space Force Is Arming to Jam Russian and Chinese Satellites

« on: April 22, 2020, 1150 UTC »

The attachment of MEV-1 to extend the life of IS-901 is a historic first.  I can think of several ways that this same technology could be used offensively.

https://www.c4isrnet.com/battlefield-tech/space/2020/04/17/intelsat-satellite-returns-to-service-after-first-commercial-life-extension-mission/

168

General Radio Discussion / Space based RDF

« on: April 15, 2020, 1347 UTC »

The downloadable screen image is interesting.  All sorts of commercial business cases for the use of RDF collected data...

https://www.he360.com/one-year-anniversary-of-pathfinder-commissioning/

169

General Radio Discussion / Lightsquared returns...

« on: April 14, 2020, 1419 UTC »

About 10 years ago, a company called Lightsquared attempted to obtain approval to offer internet services in L band, using frequencies adjacent to those used for GPS.  There was a huge backlash to this because almost all GPS receivers were not designed to work with strong adjacent signals and would be overloaded.  The combined voices of industry, users, and the DOD managed to kill the proposal.

Lightsquared was renamed Ligado, and is back.  It appears they may get the permission they desired from this administration.

Details are here:

https://www.c4isrnet.com/breaking-news/2020/04/10/fcc-to-approve-spectrum-plan-that-pentagon-claims-will-harm-gps/?

170

Equipment / L band antennas

« on: April 08, 2020, 1329 UTC »

Some good construction info here for L band antennas:

http://www.merseyradar.co.uk/airband-radio/l-band-diy-antennas-for-jaero/

171

Longwave Loggings / Re: LF 2200m amateur band propagation

« on: April 06, 2020, 1224 UTC »

The KiwiSDR built-in WSPR decoder includes a setting for the 2200M band.  I have heard a few stations here, but not as many as I have heard on 630M.

172

Huh? / Re: Damn Taxes

« on: March 30, 2020, 1154 UTC »

I just entered my interest income from my savings account, it was $10.48. I looked at the federal refund number at the top of the page and my refund went down $6. $6 on an investment return of $10.48. What in the hell!!

I can’t speak to what was going on with TurboTax, but this doesn’t make sense.  The highest incremental tax rate is 37% and this is on income of greater than $518,401 (single filer).  $6 on $10.48 would be 57%.

Speaking of TurboTax...
https://www.propublica.org/article/inside-turbotax-20-year-fight-to-stop-americans-from-filing-their-taxes-for-free

173

Equipment / Re: 120 ft T2FD Antenna Build

« on: March 23, 2020, 1335 UTC »

The March/April 2020 issue of QEX has part 1 of an article on Broadband HF Antenna designs.  In the article they note that for a 30 foot long T2FD antenna, with 100 watts input to the antenna, 74 watts is lost in the resistor at 14 MHz, and 70 watts is lost at 29.7 MHz.

Unless a flat SWR over a very large bandwidth is of importance to you (e.g. ALE scanning), the T2FD would not be my first choice for a transmitting antenna.

174

SDR - Software Defined Radio / Re: New To SDR

« on: March 12, 2020, 1158 UTC »

As there are no broadcasting stations on the long wave band in the North American countries, being a resident of the UK I've often wondered what it sounds like from across the Atlantic. The only station I've heard is Radio Algeria on 252kHz. It's weak, but you can detect audio from it. Moving to 198kHZ which is used by BBC Radio 4, there is a line on the waterfall and a very, very weak carrier wave. One night I could just detect some barely perceptible audio.

During the winter months, I often hear the European LW stations, sometimes well enough that I use them for background music while I work on other things.

175

General Radio Discussion / What is replacing Short Wave radio?

« on: March 08, 2020, 1238 UTC »

https://www.radioworld.com/columns-and-views/guest-commentaries/what-is-replacing-shortwave

176

VHF/UHF Logs, including satellites and radiosondes / Re: FLTSATCOM

« on: March 06, 2020, 1234 UTC »

FLTSATCOM 8, seen here:
https://www.n2yo.com/satellite/?s=20253
Has an inclination of 13 degrees and you can see much more N/S movement around the suborbital point.  It isn’t drifting West like FLTSATCOM 7.  My guess is that they are either moving 7 or they no longer have enough fuel for station keeping.

177

VHF/UHF Logs, including satellites and radiosondes / Re: FLTSATCOM

« on: March 06, 2020, 1226 UTC »

One other thing.  It might seem like an inclined orbit is a negative thing for a Geo, and often it is, but it is sometimes useful.   On the satellites farthest excursions North/South, it may be visible for a little while to earth sites at high latitudes that normally would never be able to see geo satellites.

178

VHF/UHF Logs, including satellites and radiosondes / Re: FLTSATCOM

« on: March 06, 2020, 1213 UTC »

Well I'm confused then because when I plug the latest keps into Orbitron it shows FLTSATCOM 8 as stationary over India near its equator moving slowly S-N every day.  If I plug FLTSATCOM 7 in, it shows it over Hawaii -- but every day it shifts west-ward along the equator.  UFO 5, 6, and 9 are similar.

OK,  that sounds like FLTSATCOM 8 is in a slightly inclined orbit, doing the figure 8 stuff.

Is it possible FLTSATCOM 7 is being moved?  To shift an orbital slot, the satellite is moved slightly closer to or farther from earth.  That causes it to move East or West.  When it gets to its new orbital slot, the satellite is parked back into the geo orbit.  This uses fuel so it is not done often.

FLTSATCOM 7 is old.  I suspect that it is just in an inclined orbit.

If you look here:
https://www.n2yo.com/satellite/?s=17181
You will see that it has an inclination of 14.5 degrees, which is a lot for a geo.

UFO8, seen here:
https://www.n2yo.com/satellite/?s=25258
has an inclination of 8.6 degrees.  There will be motion about the suborbital point, but not as much as for FLTSATCOM 7.

Compare the motion along the suborbital point for each of them.

If you compare this to, say, DIRECTV 15, as seen here:
https://www.n2yo.com/satellite/?s=40663
you will see an orbital inclination of 0 degrees and a sub orbital point that doesn't move.  This satellite has Ka band transponders and a user base that does not have tracking antennas.  It must stay in position, otherwise it will move outside the mainlobe of the user antennas.  More fuel will be expended to keep that satellite in position.

179

VHF/UHF Logs, including satellites and radiosondes / Re: FLTSATCOM

« on: March 06, 2020, 0958 UTC »

FLTSATCOM uses geostationary satellites...there is no “pass”...either your location is in the footprint or it isn’t.

Are you 100% sure about this?  FLTSATCOM 8 appears to be geo but FLTSATCOM 7 appears to be in an equatorial orbit. 

Geostationary orbits are a form of equatorial orbit.

FLTSATCOM 7 is in a geo orbit.
https://space.skyrocket.de/doc_sdat/fltsatcom-2.htm

Maintaining a geo satellite with a near zero orbital inclination uses up station keeping fuel.  One tradeoff the designer has is to allow small amounts of inclination (for example +/- 5 degrees) to develop.  Doing this means you don’t have to perform station keeping maneuvers quite so often, saving fuel and extending the lifetime of the satellite.

To the observer on earth, this results in the satellite apparently “wandering” slightly in the sky, drawing a figure 8 pattern on the suborbital point on the earth.  Maintaining a bore site on the satellite would require a simple antenna tracking mechanism, but the beamwidth of most directional UHF antennas is broad enough that this isn’t necessary.  On Ka band it would be.

FLTSATCOM 7 and 8 are beyond their planned lifetime.  I wouldn’t be surprised to if a decision had been made to leave them in place as long as they were working, but to allow them to develop some orbital inclination.

When a geo satellite is “retired” it is placed in a graveyard orbit.   This requires less fuel than deorbiting the satellite.  The satellite is pushed a few 100 km farther out than the geo orbit and left there.  This frees up that geo slot for another satellite.

Also, you are talking about FLTSATCOM 8, not UFO8, right?

180

Longwave Loggings / Re: New to longwave

« on: March 05, 2020, 1057 UTC »

Thanks.  At least I know he is still alive.  I still didn’t get a response to my latest email.  I will calling him next.

I hope you like the filter.