The SAFEX team designed built and delivered a working 2-meter station
to Mir in 1990.
Soon Mir was on the air in Voice. The Mir frequency was chose by accident. It seems the example the radio manual gave instructions on programming 145.550. During ground training, the Mir crews practiced using the example in the Manual. And that is where 145.550 simplex came from.
It is a pure coincidence that SAREX shuttle operations choose the same frequency.
The frequency 145.550 turned out to be a big success around the world.
There were few if any repeaters located in this part of the band. In
Europe the channel was near a popular Simplex channel. This was the
only known complaint.
It seemed some of the simplex operators did not like to share the channel for the 10 minute passes (maximum usage in 24 hours is less than 60 minutes of Mir activity).
The SAFEX team then upgraded the Mir station to an easy to use 1200
baud packet station.
This was an excellent decision from the SAFEX team. Now for the first time, we have an easy to use, inexpensive FM "Easy-Sat".
Beginners from around the world, could not use either Voice or inexpensive 1200 baud packet to work a satellite. The Space Shuttle was also in operation, but because of a lack of Outside antenna, the Shuttle could not be considered an "Easy-Sat".
SAFEX had done an excellent job in putting Mir Voice and Packet on the air. Stations from around the world began using Mir daily, we even got good results from fishing vessels out at sea.
It seemed that few people knew how to use the Mir Packet station properly. Most stations did not realize that the Mir PMS was a Single user Mail box. Only one stations is allowed to transmit to Mir at a time. As Mir became more popular, the ability to connect and Read or Send a message dropped to nearly Zero. The only time people could work Mir, was during the early AM hours on Weekdays, when Most people were asleep.
This was when MIREX was formed.
Dave Larsen and Miles Mann began a program to teach people how to use the Mir PMS correctly.
Dave and Miles wrote hundreds of short articles about "How to work Mir" to be published on Packet and Internet. Miles wrote two very detailed articles which were published in QST and CQVHF. After the QST article came out, many people in the USA began to start using the correct procedures.
Stations in the USA and other parts of the world became very courteous when operating the Mir PMS.
During prime time hours of 6pm - 11pm over the USA, it was possible to 6 to 10 people successfully logging to the Mir PMS and complete a transaction. This success was a direct result of the training and informaiton provided by MIREX.
Lower power stations across the USA were having excellent results when the stations all followed the same procedures defined by MIREX. And the success were not limited to stations in the USA. Many stations around the world began to follow the MIREX procedures for using the Single User Mir PMS and were having good success in their countries (South American, Australia, Canada, Asia Pacific, etc.).
From time to time, the courteous order for connecting to Mir would
fall apart for a few weeks.
This usually happened for three reasons:
I have a few reliable contacts in Europe who would send me packet log
files of Mir passes on a regular basis. It seemend the recomendations
made by MIREX on how to operate the Mir PMS station were not widely
used in Western Europe.
Hundreds of stations would constantly blast the Mir PMS with packet connect requests.
The end result, was that only the hand full of Kilowatt stations could use the Mir PMS while Mir was in range of Europe. Another problem in Europe was a station called a "Mir-Hog" .
A Mir-Hog is a station that connects on just about every pass every day and then ties up the Mir resources and prevents other people from accessing Mir.
We had a few stations like this in the USA, but they would usually go off the air soon.
Amateur Radio Stations from around the USA would send USA-based Mir-Hogs reminder to let the other beginners have a chance.
Mir was unusable over Europe, proper training would have siginifintly
reduced most of the problems.
The MIREX team did not have the resources to teach Europe. We expected the SAFEX team to be responsible for training European stations the correct procedures for using the Mir PMS.
This is when the first big mistake was made in frequency selection.
The SAFEX team incorrectly assumed that because they could not use Mir
from Germany, that Mir was receiving interference from Simplex FM
In reality, the interference caused by FM Simplex voice activity was minimal. The real cause of the inability to use the Mir PMS as primarily caused by Improper use of the Mir PMS by untrained Amateur Radio Stations.
The MIREX team informed the SAFEX team in 1995, that changing the frequency would not solve the problem. The SAFEX team would need to take a more proactive approach to training stations in Europe on the proper procedures for working the Mir Single user PMS Mail box.
The MIREX team began experiments on attempting to configure the PMS to
support multiple users.
We quickly discovered that allowing multiple connects would not solve the problem.
Multiple connects requires multiple Uplink frequencies. One uplink frequency per user. MIREX is looking into a long term fix for this problem.
In the short term, Educating the Mir PMS users is the best way to get around the Single user single frequency problem. The 2-meter Mir PMS is not designed for High volume traffic. It is a beginners satellite designed to welcome beginners to the world of Amateur Radio satellites.
MIREX began to experiment with different 2-meter channels on Mir
beginning in September 1992, when MIREX had its first School schedule
with Sergej Krikalev.
Our first school schedule was using 145.525 Simplex. However this channel did not work very well because of Packet QRM from 145.510.
At the time, Digital and Analog Repeaters were Illegal in the band 145.500 - 146.000 (USA FCC Law). Unfortunately the law is ignored, and now Packet Cancer has spread all over the 2-meter band in the USA.
MIREX was spending more time running school schedules around the
world, and we needed frequencies that would work World-Wide. MIREX
tested several channels between 144.300 - 144.500, and 145.800 -
The Mir school frequency changes were kept a secret.
We did not want the school schedules or other tests interfered with. The frequency 145.550 was still used a the Primary Public channel, as was successful world wide.
MIREX used these quite channels to conduct may types of packet tests.
We would configure the TNC modem for different parameters, to try to
optimize the packet data throughput.
We each Mir crew change, MIREX would give the new Mir crews additional training, etc.
We verified that Full two-way Packet Digi connects through Mir, were NOT practical, because it used up too much of Mir packet time to complete a simple message. Unproto proved to be much more reliable than fully two-way connects.
All of the data collected by MIREX as sent to SAFEX and SAREX. SAFEX was spending most of its time building new projects for Mir. MIREX was spending most of its time supporting and testing the existing Mir Amateur Radio Projects.
The SAFEX team never performed any extensive frequency tests with the
Space Station Mir.
The only time 145.800 was tested, was during a short Holiday week, in December 1996.
The Mir crew installed a digital voice recorder. The recorder would play a short message on 2-meter every few minutes. The system was placed on 145.800 simplex for a few days.
Then during a New Years party on Mir, the equipment was damaged and a power supply and the digital voice recorder was destroyed.
The MIREX team began to hear there were problems with 2-meter packet, when Mir was transmitting on their commercial channel 143.625. The rumors indicated the 2-meter station on 145.550 would become deaf.
The information that MIREX received about this problem was very
limited, and the problems only happened over Europe. We did not have
problems with 143.625 over the USA and were not able to analyze the
problem until 1996. Then NASA began remote comm links with Mir in
1996. Now Mir was active on 143.625 as it flew across the USA. More
Ground links were being added world wide.
Soon many populated areas of the world, would have remote Mir ground links.
MIREX began testing with the Mir crews late 1996. It was confirmed that when the commercial link was active on 143.625, it was impossible to work the Mir space station on any frequency below 145.900. The frequency 145.940, was barley usable when the ground station was transmitting more than 3000 watts of ERP. The frequency 145.985 was chosen to keep the PMS receiver as far as legally possible away from the 143.625 transmitter. (ITU regulations control satellite down-link frequency ranges).
The frequency 145.985 is still jammed by the commercial transmitter,
but intermittently high power ground stations can get access. More
testing is required to determine how much power is required to capture
the two-meter receiver.
MIREX is working on a filter project, that if approved, will solve the comm link interference problem.
MIREX still encourages stations to use as little power as possible.
SAFEX announced it would switch Mir to 145.200 uplink and 145.800 downlink on November 1, 1996.
When Mir began testing 145.200/800 in November 1996, the problems over
the USA were obvious.
Problems in many other countries were also reported, but here are the most common problem in the USA.
There are approximate 300 repeater outputs between 145.190 and 145.210. Some of the repeater outputs are even on 145.200. Previous MIREX FM satellite tests have proven, that Satellite FM requires a Minimum of 25khz channel spacing (30khz is preferred).
When Mir is listening on 145.200, Mir can hear hundreds of repeaters in its 1500 mile range. The Noise from the repeaters prevents Mir from hearing any data or voice on 145.200. When the crew used 145.800 to listen to ground stations, a similar problem occurred. It is Illegal for repeaters to used 145.500 - 146.000. Packet repeats think they are immune from the law. Now the whole area from 145.500 - 145.790 is being blasted by Packet Cancer.
AMSAT-NA and the ARRL failed to setup a buffer zone to protect the bottom of the weak-signal satellite subband.
The QRM from the packet cancer is so loud, it interferes with A0-10 &
A0-13 on SSB/CW below 145.900.
The closer you are to 145.800, the greater the amount of interference. When Mir Packet is listening to 145.800, the TNC modem hears all of the APRS packet coming from 145.790.
This QRM prevents the Mir TNC from transmitting until the built-in timers of the TNC force a packet burst every 2 minutes. When ground stations are trying to listen to Mir on 145.800, the same APRS packet QRM, prevents stations from hear Mir.
Even expensive radios and narrow band filters can not block out the packet QRM.
In April 1997 Mirex proposed a 30 day frequency test.
We would move Mir from the 145.800/200 split to 145.985 FM Simplex.
Reliable access to the Mir PMS reached an all time high during the summer of 1997.