How to build an open-source IP PBX on Satellite?
9 min readHow to build an open-source IP PBX on Satellite?
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How to build an open-source IP PBX on Satellite?
Initially it looks like an impossible taks to build an open-source IP PBX on Satellite, but decades ago, nobody would think someday a commercial company could build satellites and rockets.
Now, Elon Musk did such fantastic job and started Starlink project.
Hence, anything is possible while human technology has been making significant progress nowadays.
Why to build IP PBX on satellite?
Significantly reduces latency and improves voice quality, and increases the efficiency of PBX routing (switching).
Let’s check the possibility if we can build IP PBX with open-source VoIP technology on Satellite.
Hardware on Satellite:
What kind of CPU is used for Communication satellite?
Communication satellites use a variety of different types of CPUs (Central Processing Units) depending on the specific mission requirements and the age of the satellite.
Historically, older communication satellites used custom-built CPUs that were specifically designed for space applications, with radiation-hardened components to ensure reliability in the harsh space environment.
More modern communication satellites may use commercial off-the-shelf (COTS) processors, which are not radiation-hardened, but can offer higher processing power and be more cost-effective than custom-built solutions.
These COTS processors may be modified or shielded to withstand the space radiation environment.
One example of a commonly used CPU in modern communication satellites is the PowerPC 750, which has been used in satellite payloads from companies such as Boeing and Lockheed Martin.
Another example is the RAD750 CPU, which is a radiation-hardened version of the PowerPC 750 and is commonly used in NASA missions.
It’s important to note that the specific CPU used in a communication satellite may vary depending on the satellite’s mission requirements, power consumption, and reliability needs.
Any communication satellite is using x86 CPU?
While it’s possible that some experimental or specialized communication satellites may use x86 CPUs (Central Processing Units), it is generally not common for communication satellites to use x86 CPUs for a few reasons.
First, x86 CPUs are not radiation-hardened, which means they may be vulnerable to errors or malfunctions caused by radiation exposure in the space environment.
Second, x86 CPUs are generally power-hungry, which can be a significant constraint in a satellite where power is at a premium and must be conserved as much as possible.
Finally, the use of x86 CPUs would require significant modifications to the software and operating system running on the satellite, which may not be practical given the limited computing resources available on a satellite.
Instead, communication satellites tend to use CPUs that are specifically designed and built for space applications, with radiation-hardened components and power-efficient designs.
These CPUs may be custom-built for the specific mission requirements or may be modified versions of commercial off-the-shelf (COTS) processors that have been ruggedized and tested for use in space.
Any communication satellite is using ARM architecture CPU?
Yes, it is possible for communication satellites to use CPUs (Central Processing Units) based on ARM (Advanced RISC Machines) architecture.
In fact, ARM-based CPUs have become increasingly popular in recent years for space applications due to their low power consumption, high performance, and flexibility.
One example of an ARM-based CPU used in space applications is the LEON processor, which is a family of processors developed by the European Space Agency (ESA) and based on the SPARC (Scalable Processor Architecture) architecture. The LEON processor is radiation-hardened and has been used in a number of space applications, including satellites.
Another example of an ARM-based CPU used in space is the RAD750, which is a radiation-hardened version of the PowerPC 750 that I mentioned earlier, but includes an ARM926 core as a coprocessor for running critical software.
Additionally, ARM processors are used in many commercial off-the-shelf (COTS) products, which may be modified for use in space applications.
For example, the Raspberry Pi single-board computer, which is based on an ARM processor, has been used in some space projects.
Overall, while it’s not as common as some other types of processors, it is possible for communication satellites to use CPUs based on ARM architecture.
Sum up:
Only radiation-hardened ARM architecture CPU on SatelliteS:
- LEON processor
- RAD750
(image source: https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Onboard_Computers_and_Data_Handling/Microprocessors)
Software on Satellite:
What linux can be run on LEON processor?
One popular operating system for the LEON processor is RTEMS (Real-Time Executive for Multiprocessor Systems), which is a real-time operating system that is well-suited for embedded systems and has been used in many space applications.
Another operating system that can run on the LEON processor is Linux.
Several versions of Linux have been ported to the SPARC architecture, including Debian, Fedora, and Ubuntu.
These versions of Linux should also be able to run on the LEON processor, although some modifications may be required to optimize the operating system for the space environment and to ensure compatibility with the specific hardware and software configurations of the satellite.
It’s worth noting that the use of Linux or any other operating system on a communication satellite is subject to the specific mission requirements and constraints, and may require extensive testing and verification to ensure reliability and safety in the space environment.
Sum up:
Below Linux could be installed on LEON processors:
- Debian
- Fedora
- Ubuntu
What Open-source VoIP solution could be used for Satellite IP PBX?
Some of the more popular open source VoIP solutions include:
- Asterisk
- FreeSWITCH
- Kamailio
- OpenSIPS
- Yate
- Janus Gateway
- Jitsi
- Mumble
- Linphone
- SIPfoundry
Let’s select Asterisk and FreePBX for Satellite IP PBX
Install FreePBX on Satellite IP PBX
It’s easy way to install FreePBX by official Distro, but only for x86 architecture CPUs, so we have installed FreePBX manually on ARM architecture CPUs like LEON processors.
FreePBX officially provides detailed instruction for CentOS, Debian and Ubuntu:
What frequency do communication satellites use?
Satellite communication uses a range of frequencies to transmit information.
The frequencies used depend on the purpose of the satellite and the type of information being transmitted.
Here are some of the frequency bands commonly used in satellite communication:
-
L-band: This frequency range is used for mobile satellite services, such as satellite phones and GPS systems. The frequency range is from 1 to 2 GHz.
-
S-band: This frequency range is used for satellite communications, such as weather monitoring and military applications. The frequency range is from 2 to 4 GHz.
-
C-band: This frequency range is used for satellite communications, such as television broadcasting and military applications. The frequency range is from 4 to 8 GHz.
-
X-band: This frequency range is used for satellite communications, such as radar and military applications. The frequency range is from 8 to 12 GHz.
-
Ku-band: This frequency range is used for satellite communications, such as direct broadcast satellite television and internet services. The frequency range is from 12 to 18 GHz.
-
Ka-band: This frequency range is used for satellite communications, such as high-speed internet services and military applications. The frequency range is from 26.5 to 40 GHz.
Note that the frequency bands used for satellite communication may vary depending on the region and the specific applications.
What frequency is StarLink satellite used?
For user terminal (customer equipment) to satellite links, Starlink uses frequencies in the Ku-band, specifically the 10.7-12.7 GHz frequency range for uplink (from the user terminal to the satellite) and the 12.7-14.8 GHz frequency range for downlink (from the satellite to the user terminal).
For satellite-to-gateway links (communication between the satellites and ground stations), Starlink uses the Ka-band frequency range of 17.8-19.3 GHz for uplink and the 26.5-29.1 GHz frequency range for downlink.
It’s worth noting that Starlink is continuously evolving, and frequency bands and utilization can change over time.
Let’s set C-band (frequency range is from 4 to 8 GHz.)
How about bandwidth for satellite C-band?
In terms of bandwidth, the maximum amount of data that can be transmitted over a C-band satellite link depends on several factors, including the available bandwidth of the channel, the modulation and coding scheme used, and the satellite’s transmit power and antenna gain.
Assuming a typical bandwidth of 36 MHz (a standard channel size for C-band), the maximum data rate that can be achieved with QPSK (Quadrature Phase Shift Keying) modulation and Reed-Solomon error correction is around 50 Mbps (Megabits per second) for uplink and 100 Mbps for downlink.
With more advanced modulation schemes like 16-QAM (Quadrature Amplitude Modulation) and higher order FEC (Forward Error Correction), higher data rates can be achieved, up to several hundred Mbps for downlink in some cases.
It’s important to note that the actual achievable data rate may be lower than the theoretical maximum due to factors like atmospheric attenuation, interference, and signal degradation over long distances.
Additionally, the available bandwidth and data rates for C-band may vary depending on the specific satellite system, service provider, and geographic location.
How about ground terminals could be connected with C-band satellite simultaneously?
The number of terminals that can be supported depends on various factors, including the satellite’s available bandwidth, the modulation and coding schemes used, and the traffic demands from each terminal.
In general, C-band satellite systems are designed to support multiple terminals by dividing the available bandwidth into multiple channels that can be assigned to individual terminals as needed.
For example, a satellite with a total bandwidth of 500 MHz might be divided into several channels of 36 MHz each, which could be assigned to different earth stations as needed.
To enable multiple terminals to share the same frequency band, each terminal must be equipped with a transceiver that is capable of transmitting and receiving signals in the appropriate frequency range.
Additionally, specialized equipment such as frequency converters, up/down converters, and modems may be required to ensure that each terminal’s signals are properly matched to the satellite’s frequency and modulation scheme.
Overall, C-band satellites can support multiple ground terminals simultaneously, but the number of terminals that can be supported depends on various technical and operational factors.
The satellite operator will typically work with customers and service providers to ensure that the system is properly configured to meet their needs.
What’s C-band satellite’s connection speed and latency？
In general, C-band satellite links are capable of delivering high-speed data rates, with typical speeds ranging from several Mbps (megabits per second) to several Gbps (gigabits per second), depending on the bandwidth available and the modulation and coding schemes used.
However, the actual speed that a user experiences will depend on various factors, including the available bandwidth, the number of users sharing the same satellite link, and the specific application and usage patterns.
Latency, which is the time delay between when a signal is transmitted and when it is received, can also vary for a C-band satellite link.
Typically, the latency for a C-band satellite link is higher than for terrestrial networks, due to the longer distance that signals must travel between the satellite and the ground station.
However, with advanced modulation and coding schemes and optimized network design, it is possible to reduce the latency to acceptable levels for many applications.
In general, the latency for a C-band satellite link can range from several hundred milliseconds to several seconds, depending on the specific conditions of the link and the application being used.
Summary:
It’s theoretically possible if build an open-source IP PBX on satellite.
This would reduce costs and barriers of communication technology someday.
Let us wait and see！
