• From the Editor's Perspective: The UWB Controversy
• Letter to the Editor: UWB and GPS, a Different Perspective
• Interview: Dennis Johnson, President of Geophysical Survey Systems, Inc., about Ground Penetrating Radar
• Some Other Interesting GPR Links
• A UWB Bibliography
• Webmaster's Note: Report on Update Progress

Q. Why do you think FCC did this with GPR? Was it ignorance or are they looking at something we haven't talked about yet?

A.  I'm not sure why FCC did this. There are some real significant reasons why GPR shouldn't be lumped in with medical imaging and through-wall imaging. Both of these have a pretty strong air transmission component. We don't want to transmit in air and we should be treated differently with respect to any new rules.

GSSI and many others in the GPR community, both users and manufacturers, did get involved in the early phases of the comment process, but FCC consistently told us that GPR is known to be valuable, don't worry about it, you're OK. I think what happened, is there was such a last minute rush to make the changes covering the air transmission devices that GPR was the baby that got thrown out with the bathwater.

Q. What are the differences between GPR and the air transmission devices that make it so they should be treated differently? How do you think GPR should be handled in the Rules?

A.  There are several differences. The biggest is the one we've already mentioned - GPR is only an unintentional air transmitter. Second is pulse repetition frequency. For GPR, the operating range is 50 KHz to 500 KHz, and the air guys want to use 1 MHz to 100 MHz. Third is spectrum range - we operate from 40 MHz to 2.2 GHz, and the air transmitters usually operate a lot higher. Finally, there's a big difference in quantity - the air guys want to sell millions to a consumer market, we want to sell hundreds to more specialized commercial markets.

So from our viewpoint, there should be separate rules for GPR, and it should not be lumped in with other devices. All the GPR manufacturers should be required to have their equipment tested to make sure it conforms to Part 15 class B specs, but the user should not have to be licensed and certainly no one should have to do prior notifications before each use.

Q. What is DOD's position on GPR and the new rules?

A.  I don't think DOD was thinking about GPR when they raised their concerns about interference with GPS and other national security systems. Last week I went down to the Pentagon and talked to some of the DOD people. Part of the problem is that some of the NTIA testing to look for interference only tested at pulse rate frequencies of 100 khz, 1 MHz, and higher. GPR operates at 50-500khz. The 100 KHz testing showed no problem with interference, but no testing was done at 500 KHz, so anything over 100 is suspect in DOD's eyes. They agreed that GPR is a valuable tool for the military, and now recognize that the proposed rules are likely to cause them problems in using it. They indicated that they would support use of GPR to the FCC at a pulse rate frequency of 100 KHz.

100 KHz helps but still causes problems. Doing highway surveys, for example, we need high data density, 1 scan per inch. We take the data by towing the equipment down the highway, and to get this resolution at 55 mph, we need to use a 500 KHz pulse rate frequency. If we use 100 KHz, we can only go at 15 mph, which will seriously disrupt traffic. It's the same situation with railroad bed testing - we have to use the higher pulse rate frequency to avoid traffic disruptions.

Highway Inspection Set-up

Q. What's next? Have you brought this up to FCC since the Report and Order was announced?

A.  No, we've been waiting for the issuance of the R&O. It's possible, but probably unlikely, that the actual language will give us more operating room than is apparent from the press release and the charts. At least it may provide more clarity about what is meant.

In the meantime, we've contacted our congressional delegations - and so have the other manufacturers -- we're doing this in a coordinated manner . The user group is also coordinating their actions together. When the R&O is issued, we plan to contact NTIA, FCC, and others to see what needs to be done and what can be done to find a compromise position.

We'll be working to get testing up to 500 khz pulse rate frequency to show that there isn't any interference at this level.

Q. There's a 6month reexamination. Are you gearing up for this and how?

A.  Six months is too late - we'll be out of business if customers stop buying from us because of needing licenses and get permission for every use. A six month delay will just about completely kill the GPR industry in this country. Besides, I'm not convinced that this six month reexamination will ever happen.

Q. Anything else you'd like to add about this controversy?

A.  Our biggest shortcoming as an industry is that we haven't done enough to educate people, especially at administrative levels, about the use and importance of GPR. We have a lot of customers doing very important work, some of it related to public safety, but beyond that we're relatively unknown.

Q. Dennis, thank you very much for talking with us about this issue. It's been a real eye-opener.

A. Thank you for your interest in GPR!

1. M. Z. Win and R. A. Scholtz, "Energy Capture vs. Correlation Resources in Ultra-Wideband Bandwidth Indoor Wireless Communications Channels," 1997.
   
   
2. M. Z. Win and R. A. Scholtz, "On the Robustness of Ultra-Wide Bandwidth Signals in Dense Multipath Environments," IEEE Comm. Letters, Vol. 2, No.2, Feb. 1998.
   
   
3. J.M. Cramer, R.A. Scholtz, and M.Z. Win, "On the analysis of UWB communication channel," Proceedings of MILCOM 1999, Vol. 2, pp. 1191-1195, 1999.
   
   
4. J. M. Cramer, M. Win, and R.A. Scholtz, "Evaluatoin of the Multipath Characteristics of the Impulse Radio Channel," Proc. of PIMRC '98, vol. 2, p. 864-868.
   
   
5. J. M. Cramer, R.A. Scholtz, and M.Z. Win, "Evaluation of an Ultra-Wideband Propagation Channel," pre-print, publication soon.
   
   
6. S. S. Ghassemzadeh, R. Jana, C. W. Rice, W. Turin, V. Tarokh (authors are with AT&T Research, "Measurement and Modeling of an Ultra-Wide Bandwidth Indoor Channel", pre-print of submission to a special JSAC issue on UWB.
   
   
7. L. Rusch, C. Prettie, D. Cheung, Q. Li, and M. Ho (authors are with Intel Labs), "Characterization of UWB Propagation from 2 to 8 GHz in a Residential Environment," pre-print of submission to a special JSAC issue on UWB.
   
   
8. D. Cassioli, M. Win, and A. Molisch, "A Statistical Model for the UWB Indoor Channel," Spring VTC 2001 Conf. Proceedings.
   
   

9. Model suggested by ITU P.1238 which was described in IEEE 802.15-00/294r1.
   
   
10. Model used for the evaluation of the IEEE 802.11g high rate PHY, described in document IEEE 802.11-00/282r2 & IEEE 802.11-00/211r9.
    
    
11. Model suggested to evaluate the 802.15.3 PHY layers, described in document 00110r13P802-15_TG3-Criteria-Definitions.
    
    
12. G. Janssen, P. Stigter, and R. Prasad, "Wideband Indoor Channel Measurements and BER Analysis of Frequency Selective Multipath Channels at 2.4, 4.75, and 11.5 GHz," IEEE Trans. Commun., Vol. 44, No. 10, Oct. 1996.
    
    
13. T. S. Rappaport and S. Sandhu, "Radio-Wave Propagation for Emerging Wireless Personal-Communication Systems," IEEE Antennas and Propagation Magazine, Vol. 36, No. 5, 1994. (a survey paper)
    
    
14. K. Pahlavan and A. Levesque, Wireless Information Networks, John Wiley and Sons, 1995.
    
    
15. H. Hashemi, "Impulse Response Modeling of Indoor Radio Propagation Channels," IEEE JSAC, Vol. 11, No. 7, Sept. 1993, pp. 967-978.
    
    
16. A. Saleh and R. Valenzuela, "A Statistical Model for Indoor Multipath Propagation," IEEE JSAC, Vol. SAC-5, No. 2, Feb. 1987, pp. 128-137.
    
    
17. R. Ganesh and K. Pahlavan, "Statistical modeling and computer simulation of indoor radio channel," IEE Proceedings-1, Vol. 138, No. 3, June 1991.
    
    
18. T. S. Rappaport and S. Sandhu, "Radio-Wave Propagation for Emerging Wireless Personal Communication Systems," IEEE Antennas and Propagation Magazine, Vol. 36, No. 5, pg. 14-24, Oct. 1994 and the references therein.
    
    
19. K-W Cheung, J. Sau, and R. Murch, "A New Empirical Model for Indoor Propagation Prediction," IEEE Trans. On Vehic. Tech.,Vol. 47, No. 3, pp. 996-1001, Aug. 1998.