PROCEEDINGS
radio-astronomy.org
Society of Amateur Radio Astronomers WESTERN CONFERENCE March 11 - 13 Embry-Riddle Aeronautical University Prescott, AZ
2016
Overview of Practical Systems for Remote Control of Amateur Radio Telescopes Bascombe J. Wilson, WØAIR Little Thompson Observatory Berthoud, Colorado www.starkids.org
[email protected] Introduction Amateur radio astronomers need practical and affordable systems for remote control of receiving equipment because of rapidly increasing radio frequency interference in populated areas. While expensive, high-end remote control systems have been available to government and university installations for decades, recent advances in remote solutions for radio amateurs have immediate application for radio astronomy. In industry jargon, such systems are often referred to as Supervisory Control and Data Acquisition (SCADA), and proprietary systems are ubiquitous 1. This paper outlines several relatively simple yet effective approaches to remote control of radio telescopes that were evaluated at the Little Thompson Observatory. The Problem Pollution of the radio spectrum is just as devastating to radio astronomy as light pollution is to optical astronomy. Pollution of the radio spectrum is generally referred to as Electromagnetic Interference (EMI) or more generally Radio Frequency Interference (RFI), and the problem is rapidly getting more acute not just in industrialized parts of the world, but globally, as radio signals including unwanted ones are capable of propagating great distances. RFI can come from intentional transmitters or unintentional emitters such as poorly designed consumer, medical or industrial equipment, or improper operation of even well-designed equipment. The interference can be confined to only a few channels or widespread over virtually the entire radio spectrum. In many residential areas, the broadband RF noise level is increasing so rapidly that month-to-month surveys can actually plot the increase. The problem is so extreme in the United Kingdom that the Radio Society of Great Britain has filed a formal complaint with the European Commission. 2 In the U.S., the National Radio Astronomy Observatory (NRAO) has published helpful guidelines for industry. 3 In the U.S. and Canada, nearly every amateur radio astronomer has a story to tell about serious interference. Whether it’s from new LED and CFL light fixtures, plasma TVs, high intensity greenhouse lights, photovoltaic (solar) systems, satellites, or a myriad of inexpensive electrical and electronic gadgets with design flaws such as insufficient filtering and inadequate shielding, RFI is a serious problem that’s getting worse. While radio astronomers must not surrender in the fight to eliminate RFI, immediate protection of receiving systems is often essential. One solution is to locate receiving
equipment for radio astronomy in a more rural area where it is relatively isolated from the more egregious sources of local interference. Long range, airborne and orbital interference will still be there, but local noise can be mitigated greatly by distance and terrain. Just as optical astronomers have to retreat away from light pollution, radio astronomers are finding a need for the same strategy. Assuming a quiet location can be obtained in the country for radio equipment and antennas, the next challenge is in finding an effective way of controlling the equipment and transmitting receiver data to wherever the amateur radio astronomer happens to be. Fortunately, there are reliable and affordable solutions. Assumptions Obviously, the remote location chosen for the receiver site will need to have electrical power, moderate bandwidth network access and reasonable physical security. Each of these factors deserves consideration beyond the scope of this paper; however, it must be noted that power systems, network equipment and security sensors are capable of generating serious RFI, and design of a new facility must take these risks into account when selecting equipment. Also, the remote site will need a very reliable and stable computer, generally running 24x7 whenever the radio telescope is expected to be operational. While there are ways to turn on and boot a computer remotely, the simplest approach is to install a computer at the remote site that can be left running all the time, and use it to control the receiver, antenna and accessories. The computer system itself will usually require some form of environmental control to protect against heat or freezing. Satisfactory installations have used a wide range of computers from laptops to high-end minicomputers, and there is no reason why many essential functions could not be controlled by Arduino, RaspberryPi, or BeagleBone devices. For purposes of illustration, however, this paper will assume that the radio telescope receiver site has a desktop PC running Microsoft Windows XP or later, or Linux with an application that allows execution of Windows programs. A computer with speed of 1.3 GHz, 8GB RAM, and a 500GB hard drive should be sufficient for most situations. As with almost everything else, more is better. Most existing radio telescopes are likely to be already computer controlled to some extent, so this discussion will focus more on how to make that work remotely, rather than on getting a computer-control system set up from the beginning. A good strategy is always to get the system working perfectly with local control before attempting remote control.
Remote Control Systems As a minimum, most remote control systems will need to provide the following functions: 1. Reboot of the remote control system to clear faults 2. Control power to the receiver and preamplifiers 3. Control the remote signal processor, often software in the remote computer 4. Transmit raw or processed data back to the operator Other essential functions would likely include: 1. Switch receiver among antennas 2. Control antenna aiming or tracking 3. Adjust receiver frequency, amplifier gain, bandwidth 4. Disconnect and ground antennas for lightning protection 5. Send fault alarms to the operator Overview of a Complete System Most systems will consist of two subsystems: (1) A process to connect the control operator with the remotely located computer, and (2) A method for the operator to use that computer to control the receiver, data logging system, antennas and other essential functions. Web-based end-to-end applications such as those used by NRAO, the Skynet system, and many universities are outside the financial means of many amateur radio astronomers. While some amateur radio operators are now using elegant web-based applications for remote control, these still require considerable resources. The American Radio Relay League (ARRL) has an excellent white paper on radio remote control. 4 This paper will outline relatively simple applications that most amateur radio astronomers should be able to get up and running within just a few hours. Some users may not need full radio and antenna control, in which case a simple application such as Team Viewer (below) may be sufficient. For example, if you are using an AirSpy, RASDR or other Software Defined Radio (SDR) at the remote location and are using programs such as Radio Skypipe, SpectrumLab, HDSDR or SDR#, then all you may need is a simple control connection between the local and remote sites. In that case, one of the first three applications in the below discussion should serve adequately. For more complex installations, particularly where antenna switching and two axis drive control are needed, then the advanced applications would be justified. It is assumed that compatible computers will be running on each end of the connection and that the installer will have password access to configure the internet routers at each end. Each system requires unique router configuration to open destination ports (system address indicators) to allow proper routing of control signals and data. Installation instructions for each of the following systems give complete instructions for
required port assignments. Virtually all versions of Linux or Windows XP and later can be used as the operating system for the following applications. Connectivity and Control Both the local control point and the remote installation need reliable internet service or a direct broadband link, regardless of the approach taken. For clarity, the terms “Local” and “Remote” are used relative to the physical location of the human operator. Equipment at the operator’s location is “Local,” while distant equipment is “Remote.” The following applications will provide for connectivity, but each has strengths and limitations: 1. Remote Desktop. Both Windows and Linux have Remote Desktop applications which allow a local computer to take control of a remote one. The Help files for Remote Desktop show all the steps needed to set up and manage the connection. The remote system must have permissions enabled for remote control; the operator must know both the internet IP address of the remote system’s router as well as the LAN address of the computer to be controlled. When a connection is established, the operator can do virtually anything that could be done from the keyboard of the remote computer. Remote Desktop works equally well over a local area net (LAN) or the internet. a. Advantages: Less bandwidth required than some other applications. There is nothing else to buy or license. b. Disadvantages: Fewer control options than other applications and frequent screen freezes because of the way in which the local and remote monitors attempt to stay synchronized. Audio link is not provided, but this can be achieved by opening a Skype call between the two sites. 2. Virtual Network Computing (VNC). VNC is very similar in appearance to Remote Desktop, but the working protocols that keep the local and remote computers synchronized are more robust. With sufficient bandwidth, VNC applications will usually be more reliable than Remote Desktop and will be fully compatible with virtually any control system or other programs the user needs to run. There are some freeware versions of VNC available for Windows and Linux, but other versions require a small licensing fee. Older versions of the original open systems RealVNC are still available, and appear to be compatible with most other versions of VNC. The remote location is set up in the “Server” configuration, and the control operator’s location is set up in the “Client” configuration. a. Advantages: Reliable remote control. Cost is free to moderate. b. Disadvantages: Requires more bandwidth than Remote Desktop, resulting in dropped connections if the local and remote systems cannot stay synchronized. Audio link is not provided, but this can be achieved by opening a Skype call between the two sites.
3. Team Viewer. Team Viewer is a very good solution if bandwidth is too constrained for reliable operation of either Remote Desktop or VNC. An account must be established with the Team Viewer provider, and there are some concerns with the process by which accounts link at the central server. Team Viewer was designed primarily as a business conferencing system, allowing many partners to connect simultaneously for discussion and file sharing. Nevertheless, it works reliably as a point-to-point connection system to allow an operator to connect with and control a remote computer. Team Viewer software is installed on both ends of the circuit. The remote (radio) location is then set up with a Team Viewer account number and password, which are shared with a “partner” which would be the control operator. When a connection is established, the control operator has control of the remote computer as though locally located. a. Advantages: Minimal bandwidth required. Easy to set up and use. Bidirectional audio, video and computer commands can be sent simultaneously. b. Disadvantages: “Nagware” popup windows on the free version; Licensed version is extremely expensive ($800 minimum; up to many thousands of dollars based on configuration). 4. Ham Radio Deluxe (HRD). HRD is software that runs on a Windows PC to provide a server/client configuration for remote control without a separate overhead connection application such as Remote Desktop, VNC or Team Viewer. HRD can be used to control virtually any radio that is set up for Computer Aided Tuning (CAT) and many peripherals that can be controlled through a serial port or USB-to-Serial converter. HRD comes with a catalog of most modern amateur radio transceivers and receivers, but also allows for manual configuration to control of other equipment. HRD Versions 6.0 and above provide for Altitude/Azimuth (AltAz) control of antenna rotators. These versions also allow for two-way audio between the local and remote. Earlier versions of HRD are available as open source Freeware, but do not have the latest features. Licensing for the current version is about $100. a. Advantages: Direct control of radios, switches and antenna rotators without other overhead software. Versions older than 5.0 are freeware. b. Disadvantages: For non-ham radio equipment, considerable tweaking of the configuration may be necessary to control remote receivers. Provides a link only to radio and associated equipment, not to the remote computer’s operating system or desktop, so a separate program such as Remote Desktop or VNC may still be needed for tasks such as file transfer and program changes. 5. Remote Rig (RR). RR is a hardware system that provides remote control of radios and many peripheral devices that have serial ports, such as antenna switches. A “server” box is installed at the remote radio location and a “client” box is installed at the operator’s local location. Users most often connect a radiocompatible control head to the RR client box at the Local site and wire the client
box to the radio at the remote site. It is possible, however, to use computer control over the internet, and this is particularly useful when the radio does not have a removable control head. Antenna rotator control is possible. With a control head, it is possible to fully control the remote radio and maintain halfduplex audio between the two sites. Data compression is used to provide reasonable linkage even over dial-up connections. a. Advantages: Installation is very simple and is nearly plug-and-play. Very narrow bandwidth is required. Bidirectional audio is included. b. Disadvantages: Limited number of radio models are supported without considerable software configuration. Cost is about $500 for the basic system. 6. Internet Remote Toolkit (IRT). IRT provides web-based control over remote installations, using “Server” and “Client” software applications. While tailored for amateur radio operators, IRT can be adapted for many different receivers that have Computer Aided Tuning (CAT) features. The application was written to utilize the now-discontinued Microsoft Netmeeting program, however Skype can be substituted with good results if an audio link is needed between the sites. a. Advantages: IRT is freeware and requires only narrow bandwidth. Very easy learning curve for operators. b. Disadvantages: Supports only a limited number of amateur radios without considerable software configuration. Technical support is very limited. 7. Radio Skypipe Pro (RSP). RSP provides perhaps the easiest of all solutions for remote data acquisition and recording. By running RSP at the local and remote sites, nothing else is needed to start and stop data acquisition and to configure the many RSP parameters. Since many radio astronomers will be using RSP anyway, the program’s remote feature can be the simplest of all solutions. a. Advantages. Simple and intuitive setup. Extremely stable. Very low bandwidth requirements. Low cost for licensing. Very helpful technical support from Radio Jove community and Jim Sky personally if needed. b. Disadvantages: No control of receiver, antennas or computer. No ability to remotely reboot computer system. Security Security of any remote control system warrants some deliberate attention, as there is always the risk of malicious cyberintrusion. The threat is made more real by the robotic scanning of all internet connections by those looking to do mischief. Strong passwords provide some protection and may discourage most hackers, but if a coordinated is directed toward a given installation, it must be presumed that a determined adversary can take full control of the system and destroy or corrupt programs and data, even if no lasting harm is done to equipment. According to security specialists at SCADASystems, there are two major threats:
The principal threat is unauthorized access to software, be it human access or intentionally induced changes, virus infections or other problems that can affect the control host machine. The second threat is related to the packet access to network segments that host remote control devices. In numerous cases, there remains little or no security on actual packet control protocol; therefore, any person sending packets to a device is in position to control it. 5 The best strategy for increasing security on remote control systems is to select the highest level of encryption offered in the installation process for each application and use the strongest (longest) practical password, which is usually eight or more characters using a mix of upper case, lower case, numbers and keyboard characters. If the system runs too slowly or with errors, the administrator may have to change to a lower level of encryption, or no encryption at all in extreme situations. Regardless of the encryption choice, strong passwords should be retained. Conclusion At the Little Thompson Observatory (LTO) 6 we wanted a remote control system for our radio telescope systems so that operators could work from home to resolve issues and manage displays on the public screens without having to travel to the observatory. We installed and tested each of the applications discussed in this paper and found that VNC gave us the best results when bandwidth was not congested, but when the connection slowed, Team Viewer was consistently reliable. The radio astronomy computer at LTO runs the server application of both RealVNC and Team Viewer. Operators at home have a choice which client program to use, but most prefer Team Viewer. A final consideration for new installations relates to the Internet Protocol (IP) address of the router supporting the site. The address is assigned by the Internet Service Provider, often the cable company or wireless provider. a. The IP can be “Static” (unchanging) or “Dynamic” (subject to change anytime the ISP desires). b. With a Static IP at the remote site where the Server application is running, the operator location Client only needs to be configured once to be able to initiate connections, as the IP address will never change. c. With a Dynamic IP, the Client can connect with the Server only until the Server’s IP changes, then the Client needs to be reconfigured. There is a workaround for this: Several free and many paid services will provide IP address forwarding capabilities, so that the Client needs only to know the Server’s unique name with the forwarder, and the two will always link, no matter how frequently the Server’s IP changes. Two of the better known forwarding services are shown in the Sources section of this paper.
Sources for Software and Hardware Ham Radio Deluxe: http://ham-radio-deluxe.com/ IP Forwarding: http://www.noip.com/ Radio Skypipe Pro:
and
www.dyndns.com
www.radiosky.com
Remote control switches and other hardware: http://remoteqth.com/ Remote power switches: https://www.remotepowerswitch.com/webremotepowercontrol.html Remote Rig system: http://www.remoterig.com/wp/ Remote Rig vendor: http://www.hamradio.com/search.cfm Remote Ham Software System: http://www.remotehams.com/ Toolkit for web-based radio control: http://www.w4mq.com/ Virtual Network Computing (VNC): http://www.realvnc.com/
Notes 1
https://inductiveautomation.com/what-is-scada
2
http://rsgb.org/main/files/2011/01/PLA-PLT_M_Octavian_Popescu_2011-Jan-6.pdf
3
https://public.nrao.edu/telescopes/radio-frequency-interference
4
http://www.arrl.org/files/file/Technology/LinkRemoteControl/RemoteControl.pdf
5
http://www.scadasystems.net/
6
http://www.starkids.org
2/20/2016
Remote Control of Amateur Radio Telescopes SARA Western Region Conference Prescott, Arizona March 2016
Presented by Bascombe J. Wilson WØAIR Little Thompson Observatory
Overview •The Problem •Essential Functions of Remote Control •Examples of Practical Systems •Security Concerns •Getting Started
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The Problem: RFI •Getting Worse •Beyond our Control? •Mitigation Strategies
Remote Control Systems
•Minimum Essential Functions for RA •Cost-Benefit Balance •LTO Experience
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Remote Control System Examples •Remote Desktop •Virtual Network Computing •Team Viewer® •Ham Radio Deluxe ® •Remote Rig ® •Internet Remote Toolkit® •Radio Skypipe Pro ®
Remote Desktop •An included MS Windows Feature •Nothing else to buy or license •Allows remote control of a computer •May be good enough for your purposes
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Virtual Network Computing (VNC) •Remote control of a computer •More stable than Remote Desktop •Requires more bandwidth •Freeware and paid versions available
Team Viewer® •Remote control of a computer •Requires very little bandwidth •Very stable connections •Video and audio channels included •Free Nagware and paid versions available •Nagware popups are irritating •License fee is very expensive
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Team Viewer®
Team Viewer®
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Ham Radio Deluxe® •Remote access to radio control system •No direct access to computer programs •Very reliable and stable •Controls radio, switching, antenna drive •Packaged for ham radios…can be tailored •Audio channel included •Freeware and paid versions
Ham Radio Deluxe®
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Ham Radio Deluxe®
Ham Radio Deluxe®
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Ham Radio Deluxe®
Remote Rig® •Remote access to radio control system •No direct access to computer programs •Hardware based. Audio channel included •Very reliable and stable •Controls radio, switching, antenna drive •Packaged for ham radios…can be tailored •Cost is about $400
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Remote Rig®
Internet Remote Toolkit® •Remote access to radio control software •No direct access to computer programs •Web-based design •Controls whatever radio software controls •Designed for ham radios…can be tailored •Audio: Needs to run Skype •Freeware….but limited to no support
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Internet Remote Toolkit®
Internet Remote Toolkit®
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Internet Remote Toolkit®
Radio Skypipe Pro® (RSP) •Remote control of RSP via Admin Panel (Free version allows remote monitoring only)
•Simple, intuitive, stable •Built-in linking if IP is Dynamic •Very low cost to license •Excellent technical support Best approach if you’re just getting started
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Radio Skypipe Pro® (RSP)
Radio Skypipe Pro® (RSP)
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Radio Skypipe® Client Monitoring
Security •Always a consideration •Basic protection •Strong Passwords •Use non-standard port assignments •Don’t advertise •Be prepared for intrusion anyway •Frequent Backups •Ability to disconnect from net / shut down
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Getting Started
•Keep it as simple as possible •Test everything in one room if possible • Know Internet Protocol (IP) addresses •Biggest challenge: Router configuration
Questions? Jay Wilson WØAIR Little Thompson Observatory Berthoud, Colorado www.starkids.org
[email protected]
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