Modem replacement and
like to experiment with a configuration to allow the
simultaneous support of both 2-meter Mono band 1200
packet and 70cm mono band packet operations from the
Russian Mir Space Station. With the addition of the new
Modem, there should be enough equipment on board the Mir
station to support simultaneous dual band operations.
The existing 2-meter 1200 baud Mono band PMS station is
working very well.
The Mir PMS is the most popular Amateur Radio satellite
in the world. Because of the popularity of the 2-meter
1200 baud Mono band PMS, there is just not enough memory
or general capacity to support the large number of users.
We would like to expand the Mir Amateur Radio projects,
by adding support for a second radio band. And at the
same time, keep the 2-meter 1200 baud Mono band PMS fully
We believe it is very important to the future of Amateur
Radio Satellite operations to always keep a place for
beginners to start experimenting. The Russian Mir 2-meter
1200 baud Mono band PMS is the perfect place for
beginners to start. Over 90% of all new Satellite Amateur
Radio operators, start by learning how to use the
successful Mir 2-meter 1200 baud Mono band PMS.
of two simultaneous band operations:
station operations will not change very much. The crews
will still have voice and packet access via the 2-meter
station. The equipment configuration suggested for the
2-meter station will consist of the Icom 228 Transceiver,
connected to the PacCom HandiPacket II Modem.
This combination of equipment has already been tested for
three years on Mir very successfully.
The memory mail box capacity of the PacCom modem is very
limited, and is currently configured for 13k of message
storage. Ground stations using the Mir 2-meter PMS, will
not see any changes in the mode of operation.
portion of the project will have over 100k of message
storage capacity. Since fewer people have access to 70cm,
the amount of competition will be lower.
The success rate of the station using the 70cm PMS will
be much higher.
Mirex will transfer their daily messages to the crew
members from their family, from 2-meter to the 70cm
modem. This will help reduce the amount of traffic on the
Initially the modem will be configured for 1200 baud.
This data rate will be extensively tested to verify the
After a successful test period, the modem will be
switched over to 9600 baud RF packet data rate. Under
strong signals conditions, 9600 baud data should be
almost as reliable as 1200 baud.
Mirex will conduct extensive testing of the 9600 baud
The data rate of 1200 baud has limitations on the Size of
a file which can be transferred during an 8 minute pass.
To calculate the amount of data which can pass, you need
to take into account the Acknowledgment times for
packets, and Transceiver Switch-over delays of the radio.
Mirex has measure this value to be between 40-80
characters a second at 1200 baud or 35% to 65% efficient
, when signals are good. During an Ideal 8 minute pass,
you can upload a file of 38,000 characters.
However, this file would require the whole pass, and
signals must be perfect. Mirex has tested upload files
sizes in the range of 5,000 - 10,000 characters, with
good results during average signal conditions.
During Mike Foale's stay on Mir, Mirex sent up JPG images
of Mike's family via Packet radio.
The JPG files were carefully edited to make the files as
small as possible.
A 2cm by 2cm image usually required 5kb of data. Because
of the editing, the images were of poor quality, but it
proved that images could be send, if we can find a way to
increase the amount of data transferred.
After switching to 9600 baud FM 70cm, Mirex expects to
find similar efficiency results. The table below will
show, that even if 9600 baud signals are corrupted more
frequency than 1200 baud signals, the throughput will
still be much higher.
If 1200 baud is 65% efficient, and 9600 baud is only 35%
efficient, then 9600 baud will still be able to deliver 4
times as much data during the same time period.
During an 8 minute pass, at 9600 baud, 35% efficiency,
the Kantroncis Modem will be able to receive over 160,000
characters of data.
in Characters per Second for Mir packet
1200 42 78
9600 336 624
in Characters per Minute for an 8 minute pass
1200 20,160 37,440
9600 161,280 299,520
reason we have delayed the implementation of 9600 baud
packet, is because of the expense of the equipment and
limited availability. Most Amateur Radio equipment built
before 1995, was not capable of supporting 9600 baud data
Now most new equipment comes equipment to support higher
data rates. The cost of building or purchasing the newer
modems has been reduces and is now affordable by many
more Amateur radio stations.
The number of stations using Mir 70cm 9600 baud packet is
expected to be approximate 50 to 100 users initially.
This number of stations will gradually grow as more
people discover the benefits of 9600 baud satellite
The number of different stations using the 2-meter PMS is
over 400 stations. This huge number of stations is
causing problems with saturation and reliable access.
we support both 2-meter Mono band packet and 70cm
mono band packet at the same time with minimal
interference. If there is any interference, we
will have the opportunity to design filters which
can be used on both Mir and ISS.
we support 9600 baud mono band packet on Mir.
is the approximate efficiency rate of 9600 Mir
70cm satellite packet.
many different stations around the world can
currently support 9600 baud 70 cm packet. Mirex
has already determined from previous experiments,
that over 120 stations world wide have access to
1200 baud 70cm packet.
possible to upload and download large files to
Mir (20 - 50k files sizes).
some of the 2-meter users, over to the 70cm band.
When 70cm Packet is in operation, does the
success rate on 2-meter packet improve because
there are now two packet stations for people to
information we learn from this experiment, can be used to
help us design better systems for the ISS program.
PacCom II modem to the Icom 228 2-meter radio.
Set the Icom to the Low, 5 Watt power level.
Configure several channels into the Icom, and use
initially the 145.985 FM Simplex channel for both Voice
and packet operations.
Connect the new Modem to the Amateur Radio power supply.
Connect the new 1200 baud Data cable to the modem and to
the Kenwood TM-733 Data port. There are labels on this
cable to help identify the cable and usage. The 6 pin DIN
connector goes to the Kenwood TM-733, and the DB-9M goes
to the matching port on the KPC-9612.
The PC serial port on the has been pre set to 9600 Baud.
This rate should be the same as the existing PacCom II
Connect a Laptop PC to each Modem, one at a time and
verify that both modems can be access and the mail on the
modems, listed and read.
The command set for both modems is very similar.
externally mounted antenna on Mir is designed to support
both the 2-meter and 70cm Amateur Radio bands. The
antenna connections are very important. If the
connections are made incorrectly, one or both of the
Amateur radios may be damaged.
According to conversations I had with Mike Foale, the
radio needs to have the Antenna connected to the radio
before the power is turned on.
If the Antenna needs to be disconnected for any reason,
make sure the power supply is turned off and the radios
power cable is then disconnected.
If the power supply is turned on, while the antenna is
disconnected then a raw unfiltered 28 volts DC may surge
through the radio.
These radios are designed for a 12 volt DC system (12 -14
Filter is needed to connect both radios to the Externally
mounted Dual Band Amateur Radio Antenna. Make sure all
power is turned off to the radios and the power supply is
off, before changing any antenna coax cables.
The existing Diplexer on Mir works in the following
In the filter position, the filters in the
Diplexer are enabled. All VHF signals coming in
from the antenna port will be pass throughout to
the VHF Radio port. All other signals on the VHF
Radio port will be attenuated. Do not try to
transmit a UHF signal through the VHF Radio port
when the switch is in the Filter or Bypass
In the filter position, all UHF signals coming
from the Antenna port are passed to the UHF port.
All other signals are attenuated. Do not try to
transmit a VHF signal thought the VHF Radio port
when the Diplexer is in the Filter mode.
The Bypass mode turns off the VHF Radio port and directs
all Unfiltered signals to the UHF Radio port.
Do not Transmit any signal from a radio connected
to the VHF Radio port when the Diplexer is in the
In Bypass mode, the filter will pass all Antenna
signals, UHF and VHF to the UHF Radio port. If
the Kenwood TM-733 is connected to the UHF port,
and you want to transmit on 2-meters from the
Kenwood, the switch must be in the Bypass mode.
If the switch is set wrong, damage to the radio
Icom 228 to the VHF port of the Diplexer.
Connect the Kenwood 733 to the UHF port of the Diplexer.
Set the Diplexer switch to the Filter position.
The 2-meter transmitter on the TM-733 can be disabled to
prevent accidental transmission on the 2-meter band. Use
the following command from the Kenwood manual on page 30.
UHF Operations only.
1. Press the left [Band Select] to select the
144 MHz band. The left control select indicator will
2. Press the [VFO] button, then the [MR] button
3. Press [F] Function button, then the [CONT SEL] button
Look for the 'U2' to appear on the left Display, repeat
step 3, until the Letters 'U2' are on the display.
power supply for the Amateur Radio equipment is rated for
150 watts at 12 volts (approximately 12.5 amps). This
value is sufficient to provide the power required for the
Dual band operations providing specific settings are
Even if the transmitter output power settings are set
incorrectly, there is still a small safety margin.
Since the Amateur Radio power supply will be at its
maximum load, it is important that all other equipment be
removed from the Amateur Radio power supply.
Minimum Transmit Max Transmit Load
Full Duty Intermittent Intermittent
Icom 228 A
Low Power setting 300 ma 3000 ma
High Power setting 300 ma 6000 ma
PacCom Modem 50 ma 50 ma 50 ma
70 cm Station
Medium 'M' power setting 300 ma 4000 ma
High power setting 300 ma 8000 ma
New Modem 45 ma 45 ma 45 ma
Total Loads 695 ma 7,095 ma 14,095 ma
Safety Margin >11.5 amps >5 amps 1.5 amps over
conversations with Mike Foale, all of the wiring of the
coax cables has already been completed. The only
installation required would be to wire the new Modem to
the Amateur Radio Power supply.
David Larsen N6CO and Miles Mann WF1F would be on hand to
talk the crew though any configurations issues.
Mirex schedule times are flexible and most of the work
can be carried out on weekends. I do not expect more than
a 1 hour initial cable configuration time and 30 minutes
of crew assisted test time to complete the project.
important to carefully pick the proper frequencies to
support all of the existing Mir Amateur Radio projects
and to try to avoid any interference problems to or from
Mir commercial equipment.
There are currently two operational Mir Amateur Radio
projects and one proposed.
2-Meter PMS 145.985 FM Simplex
SAFEX II 437.950 TX - 435.750 RX
70-Cm PMS 437.900 TX - 435.025 or 050 or 075 RX
70cm PMS Transmit Frequency:
The 70cm PMS transmit frequency 437.900 was chosen
specifically to reduce the possibility of interference to
the SAFEX II repeater. The SAFEX II repeater has a set of
build in Cavity filter. These existing Cavity filters
will be sufficient to block any signal from the 70cm PMS
from causing any interference to the SAFEX II Repeater.
This transmit frequency was also chosen because there are
no other satellites using this frequency.
PMS Receive Frequency:
The 70cm PMS receive frequency was chosen to be as far as
possible away from the SAFEX II repeaters transmit
frequency. The spacing between the channels is almost 3
MHz. This wide spacing between the two channels is
required to allow both projects to operate at the same
By using the proposed frequencies, both the SAFEX II
Repeater and the 70-cm PMS should be able to operate at
the same time, with out any noticeable interference.
additional crew work load to support three (3) Amateur
Radio Experiments will not be significantly higher than
it is currently for two (2) Amateur Radio Experiments.
To help prevent crew intervention new rules will be
posted for the 70cm PMS.
of existing 2-meter PMS rules.
The public is
allowed to send mail to the 2-meter PMS, as long as the
Mail is address to the Mir crew.
The public has been asked not to use the 2-meter PMS for
The public should not send mail to other terrestrial
amateur radio stations, or publish messages to ALL.
When the crew has free time, they may read and respond to
some of the messages.
The public knows the crew is very busy, and does not have
time to answer all of the mail messages.
These rules are good and they should stay in place for
the present 2-meter PMS system.
70cm PMS will operate under different rules.
The 70cm PMS
will be designed to operate as a Third-Party-Traffic
Amateur Radio stations around the world, who can afford
to operate 70cm will now have an FM orbiting
Third-Party-Traffic will be allowed (biased on rules for
the country of transmission).
The Mir crew members will not read any traffic from the
Public on the 70cm PMB.
The Mir crew members will not send any mail to the public
(except possible bulletins by the crew).
The mail box will be maintained by the Mirex team and
other specific volunteer organizations. This Sysop
support of the Public-Mail-Box will reduce the need for
any crew involvement with the 70cm PMB.
Amateur Radio stations want to find a simple
affordable FM Public-Mail box.
The existing Amateur Radio PMB satellites (F0-19,
FO 22) require expensive SSB radios and PSK
Modems. The Mir 70cm PMB will cost less for
Amateur Radio Stations around the world to use. I
expect 200 - 300 different users per month during
the initial start of the 70cm PMB.
load on the 2-meter PMS.
Many stations are still trying to use
the 2-meter PMS to send Third-Party-Traffic.
This traffic load can now be transferred to the
Old existing Amateur Radio satellites
are beginning to Fail. We have fewer working
satellites this year than last year.
The following satellites have all stopped
operating recently A0-10, AO-13, RS-12.
The future Satellite Phase-3D, will not fly until
the year 2000.
The Russian Mir Stations can help keep interest
in Amateur Radio Satellites by added a third mode
We need to
prove that multiple amateur radio experiment can be
supported from a single orbiting space station.
When ISS is flown, it will not have one amateur radio
experiment, but it will eventually have a dozen.
The information we gain from the experiments run on the
Russian Space Station Mir, can be used to help develop
new hardware for ISS. Success or failure we will still
learn valuable information. But if we do not experiment,
will never learn.