I bought a used copy of Uplink-Downlink on Ebay. Unfortunately the quality is downright bad. Printed on what looks like bright white copy paper with a laser printer. All the images and illustrations are rasterized, the text is low resolution. The photo on the cover shows compression artifacts.
The last page reveals the culprit: "Printed in Great Britain by Amazon.co.uk " A quick search shows similar experiences with other print on demand books from Amazon. Unfortunately there's no way to tell if a book was printed on demand, most listings just show the cover image instead of a photo of the actual book. I will try to return it, if I don't have to cover shipping costs. Buyer beware... Wannes On Mon, May 25, 2020 at 4:46 PM EB4APL <[email protected]> wrote: > Hi Jim, > > This explains a lot of things. As an old time user of the Moon Bounce > time synchronization in the Madrid Space Complex, I can say that the > system was never popular among the users, it was cumbersome to use and > there were already other systems with better accuracy and availability, > such as VLBI and Loran-C. We used Loran-C as our daily reference > because we had a station at a distance of 650 Km and the signal was very > good, even with an old receiver who needed manual estimation of the > delay the results were very good. Maybe the aliens who designed the > system were not very aware of the humans idiosyncrasies > > I think that the idea was good, but the implementation was not so good. > I can summarize the "peculiarities" as I remember them: > > - The transmissions had to be scheduled for a period of common moon > view. The receiving station was manned 7/24 but the transmitting station > (DSS13, if I remember it correctly) had to be manned specially for the > event by a crew probably from Barstow, some 40 miles away. > > - Normally there were not provisions for voice communications between > the two end points, so if we did not got correlations we didn't know if > the transmitting station was working ok or even if it was not manned due > to some problem. > > - There were not monitoring aids in the receiver, so if we did not have > correlations, we has to climb to the roof, verify the pointing of the > antenna (there were a rifle scope for that), and if it was, tried to > contact DSS13 by phone and pray. > > - As you can figure it out, the antenna was not remotely controlled. One > had to climb to the roof, set the moon declination for that day using a > handwheel, slew the hour angle with a switch and select the hour angle > rate with another switch. The moon position and rate was obtained from a > nautical almanac and when the sky was clear we used the above mentioned > rifle scope. > > The receiver was quite dumb, all intelligence was on the transmitter > site. The TX equipment generated a PN code that lasted about 1s, and a > full observation cycle lasted about a minute, I don't remember the exact > figures. The code was sent advanced to take care of the round trip light > time but an additional time bias of 30 us was also introduced which was > the basis of the measurement. The bias was decreased 1us/s, so > theoretically it was received just on time in the second 30. > > The receiver generated the same PN using the station timing reference > (from a HP 5065A Rb) and it was correlated with the received code. The > output of the correlator was integrated and sent to a strip chart > recorder. The graph consisted in one trace with a quite noisy ramp and > the other trace with 1PPS from the station reference. Now the weird > thing: after finishing an observation, we put the graph in a desk and > using a drafting rule we draw a straight line that tried to be the "best > fit" to the noisy ramp. Were the line crossed the zero we read the PPS > mark there and counting back to the start of the minute we got the PPS > offset with respect to the transmitting station. Of course we averaged > the values obtained from several minutes, after discarding the noisiest > ones. > > Since we didn't had any faith in the system we didn't tried to suggest > improvements or improve it ourselves. A good one could be to use a > computer program to perform the best fit analytically, but this would > mean to type the hundreds of points manually from the graph and we never > tried this. There were not a digital version of the output, we also > could use a digital voltmeter for acquiring it. We suggested or > implemented a lot of improvements to other operational things, but this > contraption was felt as a dead horse from the beginning and its > operational life was short. Later it was replaced with a GPS based one: > 2 full height racks filled with equipment and an antenna made from a 10 > or 20 gallon hermetic paint drum for housing the front end electronics, > topped with a fiberglass radome about 1 1/2 ' in diameter. It was > painted white, but the cylinder origin was discovered during a > maintenance. It was a beautiful prototype that worked very well during > its shot life. > > I don't keep pictures of this equipment, but I have one with the same > antenna used for other purposes. > > Sorry for the bandwidth, but the thread brought me old memories. > > Best regards, > > Ignacio > > > El 23/05/2020 a las 19:17, jimlux escribió: > > On 5/23/20 9:18 AM, Mike Millen wrote: > >> Probably a good idea... there are two page 19s and no page 20 in the > >> pdf. :-( > >> > > > > > > That's the page where the aliens came and told us how to build the > > DSN, then the story resumes with 26m antenna design and operation. > > > > (If anyone's interested, I can probably ask the librarians to find it > > at JPL - correcting the pdf/microfilm is probably beyond scope) > > > > > > -- > El software de antivirus Avast ha analizado este correo electrónico en > busca de virus. > https://www.avast.com/antivirus > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
