Monday, January 30, 2012

One Radio To Rule Them All

Since the dawn of wireless, the military has fantasized about one radio that can do everything. In January of this year Wired magazine called this their "doomed quest."  The goal was to create a single radio device that can replace the numerous types of radios they use daily. In October of 2011 the U.S. Army terminated their  Joint Tactical Radio System (JTRS). The idea was to develop a software-programmable and hardware-configurable radio. Some of the spec flat out write that "The JTRS radio is to be a telephone, computer and router in one box." That sounds like a big box to me. Ultimately even reducing the requirements wasn't enough to control costs. One billion dollars later it was cancelled. So here is why it failed, and will continue to fail. More here.
  • The Unified Antenna
 The problem is that this goal works against the laws of physics. One of the more obvious goals is to have one unified antenna. Having multiple antennas on a single radio is about as ungainly as having multiple radios in the first place. But using one antenna for many dissimilar wavelengths is...well it's just dumb. Any ham will tell you that a tuned antenna is more efficient than just a random length of metal. When you design an antenna  to be effective within one wavelength, you do so to the loss of effectiveness in other wavelengths. JTRS was originally planned to use frequencies from 2 megahertz to 2 gigahertz. That's not a small piece of RF real estate. Here's a complete list :
  1. Soldier Radio Waveform (SRW)
  2. Single Channel Ground Air Radio System (SINCGARS) with Enhanced SINCGARS Improvement Program (ESIP), 30-88 MHz, FM, frequency hopping and single frequency
  3. HAVE QUICK II military aircraft radio, 225-400 MHz, AM, frequency hopping
  4. UHF SATCOM, 225-400 MHz, MIL-STD-188-181, -182, -183 and -184 protocols
  5. Mobile User Objective System (MUOS): It is important to note that the JTRS HMS manpack is the only radio program of record that will deliver terminals supporting the next generation UHF TACSAT MUOS program. 85% of all MUOS terminals are expected to be ground radios, so if JTRS HMS fails, MUOS (funded in the billions) fails as well - unless a COTS solution is developed...of course MUOS has also had its share of problems, recently announcing yet another 6 month slip for launching its first satellite.
  6. Enhanced Position Location Reporting System (EPLRS), 420-450 MHz spread spectrum
  7. Wideband Networking Waveform (WNW) (under development)
  8. Link-4A, -11B, - 16, -22/TADIL tactical data links, 960-1215 MHz+
  9. VHF-AM civilian Air Traffic Control, 108-137 MHz, 25 (US) and 8.33 (European) kHz channels
  10. High Frequency (HF) - Independent Side Band (ISB) with automatic link establishment (ALE), and HF Air Traffic Control (ATC), 1.5-30 MHz
  11. VHF/UHF-FM Land Mobile Radio (LMR), low-band 25-54 MHz, mid-band 72-76 MHz, high-band 136-175 MHz, 220-band 216-225 MHz, UHF/T 380-512 MHz, 800-band 764-869 MHz, TV-band 686-960 MHz, includes P25 public safety and homeland defense standard
  12. civilian marine VHF-FM radio, 156 MHz band
  13. Second generation Anti-jam Tactical UHF Radio for NATO (SATURN), 225-400 MHz PSK Anti-jam
  14. Identification Friend or Foe (IFF), includes Mark X & XII/A with Selective Identification Feature (SIF) and Air Traffic Control Radar Beacon System (ATCRBS), Airborne Collision Avoidance System (ACAS) and Traffic Alert & Collision Avoidance System (TCAS), and Automatic Dependent Surveillance – Addressable (ADS-A) and Broadcast (ADS-B) functionality, 1030 & 1090 MHz
  15. Digital Wideband Transmission System (DWTS) Shipboard system for high capacity secure & nonsecure, line-of-sight (LOS), ship-to-ship, and ship-to-shore, 1350-1850 MHz
  16. Soldier Radio & Wireless Local Area Network (WLAN), 1.755-1.850, 2.450-2.483.5 GHz, Army Land Warrior program 802.11
  17. Cellular telephone & PCS, includes multiple US and overseas standards and NSA/NIST Type 1 through 4 COMSEC (SCIP)
  18. Mobile Satellite Service (MSS), includes both VHF and UHF MSS bands and both fielded and emerging low Earth orbit and medium Earth orbit systems and standards, such as Iridium, Globalstar, et al. Includes capability for NSA/NIST Type 1 through 4 COMSEC, 1.61-2 [2.5] GHz. May allow use of geosynchronous satellites with special antenna.
  19. Integrated Broadcast Service Module (IBS-M). Currently three legacies UHF military broadcasts (TIBS, TDDS, and TRIXS) which will be replaced in the future with a Common Interactive Broadcast (CIB).
  20. BOWMAN, the UK Tri-Service HF, VHF and UHF tactical communications system.

Antenna efficiency measures the electrical losses that occur while it is operating at a given frequency, or averaged over its operation across a frequency band. This metric depends on three kinds of loss: coil losses, ground losses, and other losses. (Let's not get into 'other') The antenna's total resistance is the sum of these losses plus the radiation resistance , which is the effective resistance representing emitted RF power. Antenna efficiency is the ratio between its radiation resistance and its total resistance. This will always vary with the type of antenna, the dimensions of the antenna etc. !
  • A Unified Amplifier
If you are using one amplifier, it has to operate across the whole spectrum of signals you may be tuning. But the fact is that wide-band amplifiers consume much more power than narrow band amplifiers. In this case efficiency simply describes the ratio of power in to power out. Then consider that virtually all power lost in an amplifier is converted directly into heat.You can only radiate so much of that out with a heat sink and a fan. Now try to imagine doing that in a desert. Houston we have a problem.
  • Tuner Selectivity
No matter how you receive a signal, that signal must be rectified. In modern hardware we use an DPLL (Digital Phase Lock Loop) circuit, sometimes an ADPLL (All Digital Phase Lock Loop).  Undoubtedly JTRS was more vested in the even more ragged edge tech toy the SPLL (Software Phase Lock Loop.)  With these, in theory, tuning is implemented by software rather than specialized hardware.In reality it has to control hardware and it's usually just synchronizing a VFO (variable frequency oscillator) or VCO (voltage-controlled oscillator.) Spectral purity is more or less contrary to the goals of wide spectrum width, producing an inevitable loss of frequency stability, and phase noise.

But there is a solution. They should be looking at this from a manufacturing point of view. In supply chain management the answer was vertical integration. The problem here is resource management, so the answer is horizontal integration. Instead of trying a one-size-fits-all solution, merging all services, instead merge only similar services. Belligerent MBAs asking engineers to fight against the laws of physics will produce a radio the size of a refrigerator that does ten things poorly for half a million dollars each.  If you begin instead with the immutable laws of physics, start with signals that are decoded by software, who's signals can be rectified from the same or similar antennas or even modular antennas you can reduce 20 radios to 10 or even 5.