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As we all know that the 5G network of mobile communications has been officially launched, and the frequency used by 5G base stations is close to the C band of satellite communications, which will interfere with the downlink frequency band of satellite earth stations and seriously threaten the normal reception of satellite broadcasting and television signals.

Here we will analyzes various types of interference and proposes several measures for satellite earth stations to avoid interference with combined with specific cases and processing methods in actual work.

Interference types
1.1 Co-frequency interference

In some cases, 5G base stations may use a frequency range similar to that of C-band antennas. If the frequency planning is not reasonable, 5G signals may cause co-frequency interference to the signals received by C-band antennas. This will cause the quality of the signals received by C-band antennas to deteriorate, and there will be problems such as increased noise and higher bit error rates.

For example, in satellite communications, C-band satellite antennas may be subject to co-frequency interference from nearby 5G base stations, affecting the reception and transmission of satellite signals.

1.2 Adjacent frequency interference

Even if the operating frequencies of the 5G base station and the C-band antenna are not exactly the same, adjacent frequency interference may occur if the frequency interval is close. Adjacent frequency interference will distort the signal spectrum received by the C-band antenna and reduce the signal-to-noise ratio.

For example, when the transmission frequency of the 5G base station is adjacent to the receiving frequency of the C-band antenna, the out-of-band radiation of the 5G base station may interfere with the C-band antenna.

1.3 Blocking interference

When receiving weak satellite signals, the satellite receiver is interfered by a strong 5G signal next to the receiving frequency, causing the LNB of the satellite receiving link to saturate, resulting in nonlinear distortion and blocking communications.

In view of the above interference, the effect of reducing C-band antenna interference in 5G network construction can be evaluated from the following aspects:

Signal quality
-（SNR）Signal-to-noise ratio

The signal-to-noise ratio is an important indicator for measuring signal quality. When evaluating the effect of interference reduction, you can compare the changes in the signal-to-noise ratio of the C-band antenna receiving signal before and after the interference reduction measures are implemented. If the signal-to-noise ratio is significantly improved, it means that the interference reduction measures have effectively improved the signal quality.

For example, use professional signal testing equipment to measure the signal-to-noise ratio of the C-band antenna in different time periods and analyze the differences before and after interference reduction.

-Bit Error Ratio

The bit error rate reflects the error rate in data transmission. A lower bit error rate indicates a higher reliability of signal transmission. By monitoring the bit error rate changes of the C-band antenna before and after the construction of the 5G network, the degree of interference on data transmission and the effectiveness of interference reduction measures can be evaluated.

Long-term data transmission tests can be conducted to statistically analyze the changes in the bit error rate to determine whether the interference reduction measures have effectively reduced the bit error rate.

-Signal strength

Signal strength directly affects the performance of the receiving device. When evaluating the interference reduction effect, the strength changes of the received signal of the C-band antenna can be measured. If the signal strength increases or remains stable after the interference reduction, it means that the interference reduction measures have played a positive role in signal reception.

Using a signal strength measuring instrument, the signal strength of the C-band antenna is measured at different locations and time points to analyze the signal strength distribution before and after the interference reduction.

2. System performance

– Communication capacity

Communication capacity is an indicator of the transmission capacity of a communication system. If the interference of 5G network construction to C-band antennas is reduced, the communication capacity of C-band communication systems may be improved. Changes in communication capacity can be evaluated by monitoring parameters such as data transmission rate and channel utilization.

For example, conduct actual file transfer tests and compare the transmission speed and time before and after interference reduction to determine whether communication capacity has been improved.

– System stability

System stability is critical to the normal operation of a communication system. Interference may cause system instability, signal interruption, equipment failure and other problems. By observing the operating stability of the C-band communication system before and after 5G network construction, the effect of interference reduction measures can be evaluated.

Record indicators such as the number of system failures and interruption time, and analyze the changes in system stability before and after interference reduction.

– Compatibility

Evaluating the compatibility of 5G network construction and C-band antennas is also an important aspect. If the interference reduction measures can enable the two to coexist better and achieve good compatibility, then the interference reduction effect can be considered good.

Check whether there is mutual interference between C-band devices and 5G devices, and whether they can work together normally.

3. Technical indicator evaluation

-Interference power measurement

Use professional interference measurement equipment to measure the interference power level around the C-band antenna. Comparing the changes in interference power before and after the implementation of interference reduction measures, the effect of interference reduction can be intuitively evaluated.

Determine the location and number of measurement points, and take the average value of multiple measurements to improve the accuracy of the measurement results.

-Frequency characteristic analysis

Perform frequency characteristic analysis on the signal received by the C-band antenna to observe the frequency distribution of the interference signal. If the interference reduction measures can effectively suppress interference within a specific frequency range, then a significant improvement can be seen in the frequency characteristic analysis.

Use equipment such as a spectrum analyzer to draw a spectrum diagram of the signal and analyze the changes in frequency characteristics before and after interference reduction.

5G base station

Earth station /ground station
Above is the brief introduction of the impact of 5G base stations on C-band earth station antennas. Hope it is helpful for you in the future use. If you are looking for such portable flyaway antenna or any other satellite communication dish, please send Antesky an inquiry via sales@antesky.com. Thanks!

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orbital location: 119.1 E
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C band: Indonesia , Singapore, Philipines, Brunei, Malaysia, Bangladesh, India, Pakistan, Nepal, Bhutan, Sri Lanka, Uzbekistan, Tajikistan, Turkmenistan, Kyrgyzstan

If you are looking to see if there is any cross-pol interference, the example below shows how it was done. This was a routine spectrum monitoring activity. The conclusion in this case was that there were three very minor cross-polar interferers so no action was required.


Cross-polarisation interference spectrum

I was looking at the return link direction of a VSAT system involving many remote terminals each of which transmitted only very occasionally. The return link frequency range examined was 4 MHz wide, containing 10 different and adjacent frequency slots, each 400 kHz wide. At the hub there were 10 burst mode receivers, each tuned to one of the slots.

The traffic level was negligible and it was only possible to see the TDMA bursts, shown by the obvious tall spikey signals, by leaving the MAX HOLD running for many minutes.

The lower red trace, done to examine the background noise level and cross-pol interference, was obtained in just 2 seconds. No wanted bursts showed since there were no bursts happening, during those 2 seconds, when the frequency of a burst and the sweeping frequency of the spectrum analyser coincided.

The red background noise trace shows 3 steady cross-pol interferers which are detectable as increases in the noise floor of approx 1 dB, 0.25 dB and 0.5 dB. These humps, comprising interferer plus noise, compared with the background level are (C+N)/N. The interfering carriers are therefore about 6 dB, 12 dB and 9 dB below the noise level. They are not causing any problem and no action is needed. (Use this link for (C+N)/N to C/N calculation)

It was good to see that there were no significant cross-pol interferers.

Had there been a big hump somewhere it is likely that it would be associated with, and explain, poor reception (bad BER) of bursts at the corresponding return link frequency.

If you do detect an interferer it is then helpful to put a receiver directly on the opposite polarisation and see if it matches. If not, try pointing an antenna at the adjacent satellites either way along the orbit to see if you have sidelobe interference.

I hope this helps. Please add your comment below.

Best regards, Eric.

Power amplifier (PA) or up-converter power amplifier BUC (Block Up-Converter) is a device used in wireless communication, radar, and satellite communication.

Its main function is to effectively convert weak signals into strong output signals by increasing the power of the signal so that it can be effectively transmitted through the antenna.

The L-band signal output by the satellite modem can be converted into a high-frequency RF signal and transmitted back to the C-band, Ku-band or Ka-band satellite.

The performance of microwave power amplifiers/BUC(Block Up Converter) directly affects the transmission distance, signal quality and overall efficiency of wireless communication systems. With the rapid development of science and technology, microwave power amplifiers/BUC(Block Up Converter) have evolved
The evolution process from low efficiency to high efficiency is constantly driving the progress and innovation of related technologies.
1.Early Development of Microwave power amplifiers/BUC(Block Up Converter)/BUC (Block Up-Converter)
With the rapid development of semiconductor technology, solid-state microwave power amplifiers/BUC(Block Up Converter) have gradually emerged. Solid-state amplifiers have the advantages of small size, light weight, high reliability, and low power consumption, and have gradually replaced the dominant position of vacuum tube amplifiers in the microwave field. Solid-state microwave power amplifiers/BUC(Block Up Converter) mainly include traveling wave tube amplifiers (TWTA) and solid-state power amplifiers/BUC(Block Up Converter) (SSPA). Today we will introduce several major power amplifiers/BUC(Block Up Converter) includingHPA, TWTA, TWTB, SSPA, SSPB, Klystron, and BUC
2.1 HPA (High-Power Amplifier):
Function:A general term for any amplifier that boosts the power of a signal to a high level for satellite transmission.
Types:It encompasses various technologies like TWTA, SSPA, and Klystron
Use Cases:Used in applications that require high-power output to send signals to satellites, overcoming path loss in the communication channel.
2.2 TWTA (Traveling Wave Tube Amplifier):


Function:A type of HPA that amplifies microwave signals using a traveling wave tube (TWT). It’s commonly used in satellite communication due to its ability to handle high power and broad bandwidth.
Advantages:High efficiency, high power output, wide bandwidth, suitable for high-frequency (microwave) applications.
Disadvantages:Larger in size, requires more power, and generates more heat, requiring cooling.
Use Cases:Broadcast satellites, deep space communication, and high-power communication links.
2.3 TWTB (Traveling Wave Tube Block):


Function:A component or subassembly within the TWTA system that contains the traveling wave tube and associated parts.
Purpose:Focused on providing the core amplification within the TWTA unit.
Use Cases:Used as part of a TWTA system for high-power amplification of signals in satellite communication.

2.4 SSPA (Solid-State Power Amplifier):


Function:An amplifier that uses solid-state devices (e.g., transistors) to boost signal power. It’s an alternative to TWTA, offering advantages in size, reliability, and power efficiency.
Advantages:Compact, lighter, more reliable, requires less maintenance, more energy-efficient, and has better power efficiency compared to TWTAs.
Disadvantages:Typically lower power output and narrower bandwidth than TWTA, though these limitations are improving with newer technology.
Use Cases:Often used in VSAT (Very Small Aperture Terminals), low to medium power satellite uplinks, and applications where size and weight are critical factors.
2.5 SSPB (Solid-State Power Block):


Function:A subassembly or module that contains the solid-state amplification components, similar to TWTB but for solid-state systems.
Purpose:Provides the solid-state amplification within an SSPA unit.
Use Cases:Used in smaller satellite communication systems where reliability and efficiency are prioritized over sheer power output.
2.6 Klystron:


Function:A type of vacuum tube amplifier, similar to a traveling wave tube but based on a different operating principle. Klystrons amplify microwave signals by modulating an electron beam.
Advantages:Extremely high power output, excellent for very high-frequency and high-power applications (e.g., radar, broadcast transmitters).
Disadvantages:Large, heavy, expensive, requires high voltage, and has more complex cooling requirements compared to SSPAs.
Use Cases:Used in ground-based radar, broadcast transmitters, and some satellite communication systems where very high power is needed.
2.7 BUC (Block Upconverter):


Function:A device that converts a lower Intermediate Frequency (IF) signal to a higher Radio Frequency (RF) signal for transmission. The BUC typically includes an amplifier to ensure the signal is strong enough for satellite transmission.
Amplifier Type:The amplifier in a BUC can be either a TWTA, SSPA, or Klystron, depending on the power and frequency requirements.
Use Cases:Essential in satellite uplink systems, converting an IF signal (like L-band or 70 MHz) to a high-frequency RF signal (e.g., C-band, Ku-band, or Ka-band) for communication with satellites.

Modem files has been deleted. now it's not going forward from here can anybody help how to recover it either from console or winscp? please


RAM: 0x00000000-0x10000000, [0x0001c540-0x01fd1000] available
FLASH: 0x50000000 - 0x52000000, 256 blocks of 0x00020000 bytes each.
RedBoot> fis load linux
RedBoot> ^C
RedBoot> exec -c "console=ttyS1,9600 root=/dev/mtdblock2 /sbin/init 4"
Using base address 0x01600000 and length 0x00100000
Uncompressing Linux................................................................... done, booting the kernel.
Linux version 2.4.24-uc0-iDirect0 (root@EmbEserver75) (gcc version 3.3.2) #1 Wed Jun 15 12:44:25 EDT 2011
CPU: XScale-IXP4xx/IXC11xx revision 2
Machine: iDirect Phoenix Platform
alloc_bootmem_low
memtable_init
Security risk: creating user accessible mapping for 0x51000000 at 0xf1000000
On node 0 totalpages: 32768
zone(0): 16384 pages.
zone(1): 16384 pages.
zone(2): 0 pages.
Kernel command line: console=ttyS1,9600 root=/dev/mtdblock2 /sbin/init 4
Calibrating delay loop... 532.48 BogoMIPS
Memory: 128MB = 128MB total
Memory: 127388KB available (1680K code, 477K data, 72K init)
Dentry cache hash table entries: 16384 (order: 5, 131072 bytes)
Inode cache hash table entries: 8192 (order: 4, 65536 bytes)
Mount cache hash table entries: 512 (order: 0, 4096 bytes)
Buffer cache hash table entries: 8192 (order: 3, 32768 bytes)
Page-cache hash table entries: 32768 (order: 5, 131072 bytes)
POSIX conformance testing by UNIFIX
PCI: bus0: Fast back to back transfers enabled
Linux NET4.0 for Linux 2.4
Based upon Swansea University Computer Society NET3.039
Initializing RT netlink socket
Starting kswapd
JFFS2 version 2.1. (C) 2001 Red Hat, Inc., designed by Axis Communications AB.
i2c-core.o: i2c core module
i2c-dev.o: i2c /dev entries driver module
i2c-core.o: driver i2c-dev dummy driver registered.
i2c-algo-bit.o: i2c bit algorithm module
i2c-proc.o version 2.6.1 (20010825)
pty: 256 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with MANY_PORTS SHARE_IRQ SERIAL_PCI enabled
ttyS00 at 0xff000003 (irq = 15) is a XScale UART
ttyS01 at 0xff001003 (irq = 13) is a XScale UART
Universal TUN/TAP device driver 1.5 (C)1999-2002 Maxim Krasnyansky
Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
ixp425_init: Window Size = 33554432
IXP425 Flash: Found 1 x16 devices at 0x1000000 in 16-bit mode
cfi_cmdset_0001: Suspend erase on write disabled.
Using buffer write method
Creating 6 MTD partitions on "IXP425 Flash":
0x00000000-0x00040000 : "RedBoot"
0x00060000-0x00160000 : "Linux"
0x00160000-0x01fe0000 : "RootFS"
0x01fe0000-0x01fff000 : "FIS directory"
mtd: partition "FIS directory" doesn't end on an erase block -- force read-only
0x01fff000-0x02000000 : "RedBoot config"
mtd: partition "RedBoot config" doesn't start on an erase block boundary -- force read-only
0x01fe0000-0x02000000 : "FIS Overlap"
Board has 65nm flash part
pktgen.c: v1.3: Packet Generator for packet performance testing.
pktgen: Error: your machine does not have working cycle counter.
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP, IGMP
IP: routing cache hash table of 1024 buckets, 8Kbytes
TCP: Hash tables configured (established 8192 bind 16384)
IPv4 over IPv4 tunneling driver
GRE over IPv4 tunneling driver
Linux IP multicast router 0.06 plus PIM-SM
ip_conntrack version 2.1 (1024 buckets, 8192 max) - 320 bytes per conntrack
ip_conntrack_pptp version $Revision: 1.1.1.1 $ loaded
ip_nat_pptp version $Revision: 1.1.1.1 $ loaded
ip_tables: (C) 2000-2002 Netfilter core team
ipt_time loading
ipt_recent v0.3.1: Stephen Frost <sfrost@snowman.net>.  http://snowman.net/projects/ipt_recent/
arp_tables: (C) 2002 David S. Miller
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
IPv6 v0.8 for NET4.0
IPv6 over IPv4 tunneling driver
ip6_tables: (C) 2000-2002 Netfilter core team
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
Other stuff added by David S. Miller <davem@redhat.com>
NetWinder Floating Point Emulator V0.97 (double precision)
VFS: Mounted root (jffs2 filesystem).
Freeing init memory: 72K
Kernel panic: No init found.  Try passing init= option to kernel.

As we know that satellite communication system is kind of open system and the main usage is to transmit signal. It means that satellite communication system is easier to be interfered by some outside factors.

Let us show you more details of causes and solutions about satellite communication interference.In general, common interference include polarization interference, power interference, forwarding interference, spurious interference, FM interference, frequency sweep interference, intermodulation interference, and the use of frequency bands. Today, we will focus on the first three interference types, including polarization interference, power interference and forwarding interference.

Before introducing these three interference methods, let us first discuss the possible causes of interference. Based on our years of experience, there are 4 main reasons as follows.
1.Why does interference occur?
uplink station
Signal transmission route
The satellite itself.
Downlink station
2.Interference introduction and its solutions
2.1 Polarization interference

What is polarization interference? To understand polarization interference, we must first know what polarization means?

The electric field direction of the electric wave is horizontally polarized wave, and the electric field direction of the electric wave is perpendicular to the ground.

The same frequency can use horizontal and vertical polarization at the same time without interfering with each other. Therefore, in satellite communication, satellite companies can use polarization for reuse. When designing satellites, dual-polarization design is adopted to double the satellite capacity.

The polarization method in satellite communication depends on the polarization of the antenna. Signals in a satellite communication system require at least three antennas: an uplink station antenna, an antenna on the satellite, and a receiving station antenna. (If there are two antennas for sending and receiving on the satellite, it is at least four antennas.) The polarization of the three antennas is matched to achieve the effect of co-frequency multiplexing without affecting each other.

For satellites, when designing a satellite, specific index requirements are put forward for the antenna on the satellite. The polarization isolation in the coverage area is more than 30dB, and the main service area reaches 40dB. After the satellite is launched, the attitude basically remains unchanged and maintained in a good state for a long time.

For the uplink station and the receiving station, since the earth is a sphere, some changes will occur in the horizontal and vertical directions of the ground, and the angle of the antennas at different locations must be adjusted to match the satellite.

polarization angle

Uplink Polarization Interference
The polarization of the uplink antenna can not meet the requirement, or the polarization angle does not match the satellite. For example: if you use horizontal polarization, because the polarization angle is not adjusted properly, part of the signal leaks to the vertical polarization, which will cause interference with the vertical polarization of the same frequency, as shown in the figure below.

spectrum shows that the polarization angle is not adjusted properly

This spectrum shows that the polarization angle is not adjusted properly

To avoid uplink polarization interference and use the satellite in compliance, please contact the satellite company, designate the frequency band to send a single carrier, guide the rotation azimuth, elevation and polarization angle, and record the angle. If the location changes, contact the satellite company to re-calibrate the polarization access network, see the following picture.



Spectrum when adjusting polarization of a transmitted single carrier

Downlink polarization interference
The polarization of the receiving antenna is not up to standard, and the main polarization and anti-polarization signals are received at the same time, and the same frequency interferes with each other.

For example, it was intended to receive the horizontal polarization signal forwarded by the satellite, but the polarization Angle of the receiving antenna was not properly adjusted. When it received the horizontal polarization signal, it received the normal vertical polarization signal, which resulted in the interference between the received signals and could not be used.

To avoid downlink interference is mainly to adjust the polarization of the downlink station. (Specific method: use the spectrum instrument and other equipment to directly connect the polarization of the receiving antenna, to receive a beacon corresponding to the satellite polarization, rotate the polarization Angle, the beacon energy modulation is maximum. If conditions are available, connect the receiving antenna to another polarization, the receiving satellite should be relative to the polarization beacon, rotate the polarization Angle, and adjust the beacon energy to the lowest; If you do not have a spectrum analyzer and other equipment, use demodulator, beacon machine and other equipment to ensure the best state of receiving signals. If the antenna has uplink capability, you can also contact the satellite company to calibrate the polarization)

Polarization interference can also cause interference over time, and indicators need to be re-measured if the earth station is moved. Long time not to the satellite, pointing error is too large. Polarizer, duplexer shifted, out of position, damage to the feed, feed filling with other substances can cause interference as well.

Hello, in case you need any of the below items I have them in stock.

1. CDM 625A with 20mbps CnC, with other advanced options.
2. CDM 625A with 15mbps CnC with other advanced options.
3. CDM 625A with 10mbps CnC with other advanced options.
4. Some units of CDM 625A no CnC but other advanced options.
5. CDM 625, no CnC but has other advanced options.
6. Some units of 570L modems.
7. 48volts comtech power card.
8.  Lots of MDX 420 satellite network gateway modems.
9. Other iDirect modems.

Kindly contact me on whatsapp/Call at +234 806 350 4879 or email: chidonwokeafor@nexemtech.com

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Hi, I have CDM 625A, one with 20mbps, another with 15mbps, another with 10mbps and another with 5mbps, all used. Contact me on +2348063504879 if interested.

Thank you Eric!

Yes, we did checked all of them indeed, most of them dont have the required module, others are still to check and others didnt reply our multiple messages...

Thank you so much!