things, such as E-911 location assist.
This ranging system?
with 259.7MHz and 298.6MHz carrier frequencies?
Lists GPS as using 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal) carri er frequencies. The history of GPS doesn't mention the Apollo ranging syste m at all, which does make sense because GPS is designed to serve any number of users. and Apollo never had more than one at a time.
-- Bill Sloman, Sydney
snipped-for-privacy@optonline.net wrote in news: snipped-for-privacy@googlegroups.com:
You have a maturity problem.
You are so good at googling or so you think. Look up integrated circuit you retarded putz.
And you jacking off at the mouth about the use of the term "discreet wired" proves that you are an idiot too, as it is widely used in the electronics industry, you pathetic little putz.
Bill Sloman wrote in news: snipped-for-privacy@googlegroups.com:
1967 is NOT 1960.Bill Sloman wrote in news: snipped-for-privacy@googlegroups.com:
All of those 'specs' did not even come out until the '70s.
Some chip makers' main lines were the high performance mil grade ceramic carrier parts.
I beg to differ (again). NiMH and LiIon batteries are good for 700 to
1000 charge cycles. Lead-acid batteries, about 300 cycles. NiCd is good for at least 1000 and with a properly controlled charge cycle, can easily do 3000 or more cycles. Properly treated, they can last almost forever: "NiCd Battery Still Runs After 28 Years"So why do NiCd batteries have such a bad reputation for short lifetime? The problem was that when NiCd batteries initially arrived in the late 1960's and 1970's, the charging systems were really crude. At best, they had some kind of heat sensor on the cells to terminate charging when the battery became warm. That doesn't work very well. I've can cram 5C or more charge current into a NiCd cell without heating or damage at up to about 85% of full charge. From there, the cell gets warm and eventually quite hot. Once warm, the cell is damaged or dead. So, terminating the charge cycle when the battery gets warm is a really bad idea. There were a bunch of other schemes that worked to varying degrees. Some could be tricked by starting a new charge cycle with a fully charged battery. Most chargers had no intelligence of any kind and would charge at very slow rates on the assumption that the low current could not overheat and kill the battery.
There was also the problem of charging cells in series. With equal current going through the series string of cells, the voltage across each cell and the heating would depend on the internal resistance, which could vary considerably. That resulted in overheated cells, and occasionally a reverse charged cell. What was needed was todays balance charger, as is popular in RC model airplanes, robotics, and LED flashlights. Laptop batteries use a BMS (battery management system) which also provides charge equalization. All this would have been very useful protecting the early NiCd batteries.
So, if NiCd's were really so wonderful if properly charged, what killed their popularity? Mostly, it was the cadmium, which is designated a hazardous substance and pollutant. What was needed was something more environmentally friendly. NiMH and some (not all) LiIon chemistries provided the necessary replacement.
However, in the early 1970's, NiCd was still an acceptable technology. Had NiMH and LiIon not been invented, and someone invented a successful BMS, cell phone batteries based on NiCd chemistry would have worked quite well. We would not have had Apple iPhones with non-replaceable batteries, which is good thing. The phones would have been larger and heavier, but that would have been tolerated pending the invention of lower power radios.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
but still not all that wonderful, but useful enough for special application
"Fairchild went forward and created IC chips for use in the Apollo spacecra ft which went to the moon. It was this program along with using chips for s atellites that spread the IC from military applications to the commercial m arket. It also lowered the price of the IC drastically which made it perfec t for use in many electronic devices."
It took p-n isolation to get to the kind of parts we use today.
"Noyce, who stayed at Fairchild, used an idea from Kurt Lehovec, who worked at Sprague Electric, to create the p-n junction isolation."
I was working at Kent Instruments in Luton when Motorola and RCA got their yields high enough to start the price war that dropped integrated circuit p rices to point where it was cheaper to use them than discrete transistors, around 1975.
The parts cost for a circuit I designed dropped from 50 UK pounds to 15 UK pounds between time I'd completed the design and the time - about a month l ater when the printed circuit layout was completed and the design was relea sed to production. It was a really low volume product, so the parts cost wa sn't all that interesting.
-- Bill Sloman, Sydney
When exactly does a radiotelephone network become a cellular network ?
The number of channel has always been limited so the base stations have to reuse the channels at say 100 km distance from each other.
Does a radiotelephone network become cellular, when two mobile units in different areas can communicate wit each other through leased land lines ?
Is a manual/automatic connection to the general landline telephone network required ?
Must the base station automatically command the mobile station to use the minimum power required to perform the communication, in order to minimize spillover to nearby cells ?
On a sunny day (Sun, 21 Jul 2019 21:28:50 -0700) it happened Jeff Liebermann wrote in :
Indeed, I still have one nicad AA and a few month ago tested it after some discussion about those on Usenet. Still working OK,. Minus is the large self-discharge and lower capacity than modern batteries. But I keep it. An other one I have is for SRAM backup here:
So >> 34 years. The AA is even older, maybe from 1983 or so.
The ranging system used in Apollo is now known as two way ranging and is used in all planetary probes these days.
While GPS also uses PRN codes, it is essentially a one way system.
In the early days, that was mainly a US only problem with their minuscule boosters, some of which were merely V2 derivatives.
The Soviets had a big dumb booster (Sputnik/Vostok/Soyuz) so they did not have to watch every gram and could use more or less off the shelf components and equipment.
snipped-for-privacy@downunder.com wrote in news: snipped-for-privacy@4ax.com:
The worry was not the weight. I should have said mass.
The launch G forces break circuit connections.
Jeff, the first Mobile Telephone I repaired was in a briefcase. It was owne d by a local doctor, and the original batteries had failed after years of s ervice. It used six Gates 2V lead acid cells. That was in 1975 I think. It could also be operated from a cigarette lighter cord. It looked more like T elemetry equipment than a Phone. :)
snipped-for-privacy@downunder.com wrote in news: snipped-for-privacy@4ax.com:
did
shelf
There was no such thing as "off the shelf" back then. Especially not for us and certainly no big electronics industry existed in the old USSR, everything was from a mil or aerospace root. We had ZERO "COTS" in use until it was adopted.
Solder joint size/weight/mass is a vibrational survival thing, not an overall payload thing. So the connection count is an important factor when 99.9 percent of failure modes are from continuity breaks. So a discrete wired assembly has to be constructed to survive vibe if it is going into space.
You've snipped a whole lot of stuff which went back rather earlier, which makes you a cheat as well as a dope.
If you want to cheat, try to be less obvious about it.
-- Bill Sloman, Sydney
Rubbish. The data sheet for the uA709C that I bought - off the shelf in Aus tralia in 1967 - included the specifications for the industrial and militar y specification parts.
Most of the early parts seem to have designed for specific customers. Some were more widely useful than others, and the chip makers who got stuck with the less general purpose parts might have ended up selling only to the mil itary customers who had commissioned the original part.
-- Bill Sloman, Sydney
one.
ologies
rs.
The principle of a cellular network is that adjacent cells always use sligh tly different frequencies, and the transmitted power is adjusted so that no n-adjacent cells re-using a given frequency don't interfere with the closes t nonadjacent cell using the same frequency.
The moving phone keeps track of enough frequencies to know when to switch s witch from the fixed station in one cell to the fixed station in the neares t neighbour cell.
The idea of cycling through a limited collection of frequency bands is the central feature of cellular networks.
It is built-in. The mobile phone talks directly to the station at the centr e of the nearest cell which sets up a - mostly landline - connection to the telephone at the other end of the call.
That would seem to be an essential capacity. Cell sizes are limited both by the range that can be covered by the transmitter power capacity built into the mobile part, and the number of mobile phones active with a particular cell.
Country cells are a lot bigger than inner-city cells.
-- Bill Sloman, Sydney
No. That one was for the CSM->LM range, and was piggy-backed on the existing signal between the two. There were multiple VHF links, including two each on the astronaut's suits.
259.7 was used from EVC-1 to EVC-2 and the LM. 296.8 (not 298.6) was used from the LM to the suits. 279.0 was sent from EVC-2 to EVC-1.Anyhow, no, not those links.
The ranging system was sent as a PRNG directly phase-modulated onto the S-band carrier (2287.5MHz) at a bit rate of 992kbps. The spacecraft demodulated it and used it to immediately modulate the download the downlink (2106.4MHz) same way.
The sequence of PRNGs was used with Chinese numbers to quickly search for the maximum correlation, stepping through progressively longer-sequence PRNGs
Duh. It's the same thing, upside-down. One spacecraft, multiple ground stations (triangulation only useful at certain ranges near earth due to baseline length and visibility). One GPS receiver, multiple (moving) satellites. It's the same thing.
Clifford Heath.
They didn't have an atomic clock on the Apollo, nor a ground computer capable of the relativistic calculations needed. The downlink was frequency locked to the uplink to cancel the doppler effect on ranging, so relativity didn't need to be accounted for.
That's immaterial - using an uplink is just another way of getting the spacecraft to send a reliable signal, plus it doubles the resolution.
Clifford Heath.
r
arrier frequencies. The history of GPS doesn't mention the Apollo ranging s ystem at all, which does make sense because GPS is designed to serve any nu mber of users. and Apollo never had more than one at a time.
For a rather generous interpretation of "the same thing".
If the GPS history on Wikipedia is anything to go by, the Apollo ranging sy stem is just one of many that was around at the time, and not all that rele vant to the development of GPS. I can't recall a single mention of an atom ic clock in the Apollo write up, and there is one in every GPS satellite.
If you haven't got much grasp of what's going on. Apollo didn't seem to nee d general relativistic correction, GPS wouldn't work without it.
-- Bill Sloman, Sydney
But GPS can't use it, because there's no way of getting a signal back from the ground receiver to the orbiting transmitter.
Let's face it - your grasp of what GPS does and what the Apollo ranging system did is remarkably superficial.
They are "the same thing" to about the same extent as Model T Ford is the same thing as a Tesla.
-- Bill Sloman, Sydney
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