V one article to cover the whole direction of the amateur hobby - it is impossible to work through satellites. I will dwell only on the most difficult moments - various methods of working through FM and SSB satellites and correction of the Doppler effect .

About the types of transponders

The transponder in a broad sense is a radio confront, that is, a radio transmitting device that sends an outgoing signal upon receipt of an incoming signal.
In the amateur satellite service, Transponder is the signal retranspace placed on board the satellite from ground amateur radio stations.

All satellites use Cross-band (from English "CrossbaND " - through the range, interdiapasic) relayers. Transfer to the radio amateur satellite " from the bottom up " in the range of 432 MHz, and receiving " from top to bottom " by 144 MHz. Or vice versa: 144 MHz - up, 432 MHz - down.

Satellites are FM, linear and linear inverting transponders.

FM satellites use the only channel - all radio amateurs work on the relay in turn the same as in a regular repiter. Examples: SO-50, FOX-1D (AO-92). Dignity: simplicity and accessibility. Disadvantage: Often the same correspondents with strong signals at each turn occupy the frequency and do not allow weak stations to work.

Linear SSB/CW Transponders - a plot of about 20-300 kHz is allocated. The entire entrance strip is transferred to another range without changes and processing - where the reception is carried out.
The advantage - dozens of radio amateurs can work on a satellite, there is no crush. The disadvantage - to make the correction of the Doppler effect, either expensive transitors, such as the IC -9100, or control with the help of a PC - due to the Doppler effect are required.
Examples: AO-7 Mode A.

Linear inverting - additionally change the type of modulation - if at the entrance the modulation of LSB, then at the output of USB, and when rotating the setting handle above the frequency on Uplink, она понижается на Downlink. Это 99% всех SSB/CW satellites. Example: FO-29, XW-2A, AO-7 Mode B.

To work through satellites in a transiver, two VFO (smooth range generators) are used)
* Main * - on a reception in USB (download, descending channel of cosmos -land)
sub ** - for transmission in modulation LSB (UPLINK, the rising communication channel Earth -Cosmos)

In some transceivers, for example, Yaesu FT-817, FT-857 is vfo-a and vfo-b . On the use of two VFOs, the work is based on "Split" ( split )-VFO-A, for VFO-B transmission, frequencies in different ranges are used to receive. In the beginning, you need to configure the VFO-A (Main) frequency, then cross the VFO-B (SUB) and configure the transmission and press the Split key-both frequencies will be involved in each in turn (reception and transmission).

Satellite work procedure

The antenna should be the entire period of visibility at the Azimuth satellite (for low orbits up to 60 degrees, you can use fixed elevation of 30-45 degrees ). It is necessary to put the antenna along the azimuth manually or with the help of a rotor (possibly with a controller and control from a computer). The work is carried out in the same way as on VHF - the call sign of the correspondent and its own, then a brief greeting 59 and its QTH locator. The transmitted power should be small - usually 2 W (in extreme cases 5 W) - because At the transponder receiver, with a strong signal, it will lose sensitivity. Increasing the angle of space (elevation) over 30 & Deg; It is necessary for acute antennas - more than 5 elements, or antenna grates ("glass").

Satellite work techniques

1. Historically, the first method of work through linear satellites CW/SSB

For reception, the second CW/SSB transceiver or a control receiver is used. This is the mode of the duplex (I hear and transmit at the same time).

1. On the transmitter, set the frequency of the _ -by
2. At the receiver, install the outgoing frequency (descending channel or download)
3. By rotating the handle of the transmitter setting and while on the program, choose the frequency of program to comply with its receiving frequency. To do this, the telegraph is transmitted by a series of points and the settings handle smoothly changes the transmission frequency, until they find where the sm of themselves is heard.
4. Transmit CQ or respond to a call.

The advantage of this method is
*Any transceiver can be used for transmission, even without a CAT interface (just know input and weekend frequencies of popular satellites).

• Full duplex - self -control and convenience of controlling your signal
• Confidence that you can be heard.

Lack of the method:

• It is inconvenient to switch from a satellite to a satellite, because There is no frequency memory.

2. The hardware method of working through a satellite in modern transceivers

Correction of frequencies and transmission to compensate for the Doppler effect is carried out by the radio station (such as the ICOM IC-820, IC-910, 2000, IC-9100, IC-9700 or Kenwood TS-2000). In the memory of a radio amateur receiver, you can store duplex couples of receiving and transmitting satellites.

There is the possibility of setting the law of change in the frequency of Normal or Reverse.

1. Changing the frequencies of gears and receiving simultaneously (normal) in one direction.
2. A change in the transmission frequency leads to the same reduction in the frequency of reception.

Disadvantages: only duplex pairs of satellite frequencies are stored in the memory of the radio station. The law of amendment is set manually by pressing the Normal/Reverse button. With the incorrect pressing, the station will not be in place, but to run in the opposite direction, enhancing the effect of the doppler.

Procedure:

1. During the transfer on Main VFO, they find free space on the transponder and "stand on a general call."
2. They switch to SUB change the transmission frequency to hear your signal through the Main receiver.
3. During the QSO, using the setting handle, change the SUB transmission frequency, controlling your signal through Main so that the voice or CW is all the time at the same frequency.

   This is the so -called "look test", i.e. The through test of the entire tract transmission - satellite - reception.

4. If the signal of the correspondent at the reception “floats” a little, we increase the intelligibility with the inclusion of the distillation of the third heterodin (RIT). A separate Rit handle allows you to adjust the signal deviation up to +-10 kHz at the reception (if there are no rit handles, we simply adjust the frequency to Main). In this case, the transmission frequency to Sub should not be touched.

3. The modern method is the adjustment of the transfer frequency with the control of the reception using a broadband USB receiver with a panorama function

It is a variant of the very first way. But here, instead of a control receiver, a USB “whistle” type Funcube Dongle Pro (FCDP) or cheaper RTL-SDR 2832U (tuner R820T) with programs like SDR# or GQRX is used. To answer the call (CQ) of another station, you also need to “fit” _ your signal using the transmitter to the receiving frequency (at which the calling station works), observing the spectrum or by ear. Further, QSO is carried out at the same frequency.
The disadvantage of this method is to overload the receiver during the transmission (we need a high -quality strip filter at the inlet of the receiver).

4. Improved method No. 3 - the drift is additionally adjusted due

ДовThere is an “ugly” method, but you can’t do without it when you need to completely suppress the effect of a doppler, for example, when taking weather pictures or when taking PSK signals or AFSK9600. Once I managed to configure this method according to someone else's instruction. The method is used in Satnogs automatic reception stations - you set it up once and do not touch it anymore. :-)

Under Windows:
The WXT program is neededrack, плагин WISPdde к SDR SharP.
https: //www.qth.spb.ru/forum/Viewtopic.php? F = 30 & t = 8264 & p = 136943#p136943
A similar way is using SDR# with Wispdde plugin, but the program is Orbitron.
https: //r4uab.ru/sdrsharp-orbitron-dde-tracker-sdrsharp-satellite-tracking/

5. The modern method is the calculation of the Doppler shift and the frequency correction using a computer

Foreign radio amateurs prefer SatPC32 for Windows - simultaneously controls the rotor and adjusts the Doppler shift. The SATPC32 program has ICOM transceivers.

6. The method of working through the satellite described in the guidance of the user Yaesu FT-857

Since in yaesu FT-817 и FT-857 нет дуплекса, для FM спутников используются заранее запрограммированные пары частот на прием и передачу с учётом ранее рассчитанного эффекта Доплера. Применяют значения частот для начала прохождения спутника, середины и окончания видимости, с двумя промежуточными вариантами, всего 5 пар частот. Здесь используются пары VFO-A и VFO-V, работа сплитом. Сплит обеспечивает очень быстрое переключение приём-передача. Но можно использовать сохранение двух разнесенных частот приема и передачи в одной ячейке памяти, как это можно сделать, например, в Yaesu VX-6r. Недостаток Yaesu FT-817/857/897 - There is no self -control (feedback) due to the fact that the radio station is intended mainly for working in a campaign, and not on satellites.

7. Working option through FM-retranstants using two radio stations

It is more convenient, improved option No. 6 - there is feedback and self -control, but is only suitable for FM satellites.

The first radio station - for transmission

The second radio station - for reception

Sources:

https: // www.amsat.org/two-way-satellites/so-50-satellite-information/
https: // www.amsat.org/ao-92-commissioned-open-for-amateur-use/
https: // www.amsat.org/ao-92-commissioned-open-for-amateur-use/
https: // www.amsat.org/wordpress/wp-content/uploads/2014/01/LilacSaT2_info-20151007.pdf

Last change: 21.04.2025.

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