Coyote Dual Modular Receiver System

The Coyote™ is a high performance, modular receiver system providing two unique and independent RSSI measurements using precision dual receivers. Coyote™ is designed from the ground up to provide hot-swappable components including removable/rechargeable Li-Ion battery, Compact Flash® storage, removable 12-channel GPS receiver module and two removable receiver modules. Optional, GPS-based Forecaster™ mapping software makes Coyote™ the most comprehensive receiver system available to engineers today.

Download a technical paper on 40 Lambda Conversion
Download Coyote data sheet
Download Coyote manual from the Technical Support section

USB Compliant
 

Features

• Multiple bands supported including Wi-MAX, Cellular, GSM, LMR, PCS, ISM, WCS, MMDS and more
• Dual modular receivers allow users to swap various bands while in the field
• High measurement rate, more than twice that of Dr. Lee's recommended 40 lambda
• Removable 12-channel/12 satellite GPS modular receiver with active antenna
• Removable rechargeable Li-Ion battery system found on standard PC laptops
• Removable Compact Flash (64MB card included) memory system for data storage
• Captured data output via USB and serial ports for connectivity to any PC
• Optional GPS-based mapping Forecasterª PC software
• Weighs only 7 pounds fully loaded

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Specifications

Frequencies

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Software

Coyote Data Logger Measurement Screen
 

Coyote Data Logger GPS Screen
 

Coyote Channel Table Editor Screen

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Options

Forecaster PC software allows Coyote to overlay all drive-study measurements for overall RF coverage.

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FAQs

What is the significance of Rayleigh Fading in coverage measurements with 40 Lambda criteria?

There are two types of fading that are relevant to performing coverage measurements, fast fading, also know as Rayleigh fading, and terrain based fading due to obstructions and propagation loss. The goal of coverage measurement is to measure the local signal strength in presence of terrain based fading.

Rayleigh fading is due to close in reflections. It produces drops in signal strength that are only a fraction of a wavelength in size (often on the scale of inches). These fades always exist and are only of interest in the sense that coverage measurements must be made in a manner that rejects Rayleigh fading, so that actuate measurements of terrain based fading can be made.

William C. Y. Lee derived a well accepted criteria for removing Rayleigh fading and retaining slower terrain based fading, known as 40 Lamba averaging [W.C. Y. Lee and Y. S. Yeh, “On the Estimation of the Second-Order Statistics of Log Normal Fading in Mobile Radio Environment”, IEEE Trans. Comm., vol. 22, June 1974, pp. 869-873] (You can find an easier to read version of this criteria in most mobile communications text books). In order to remove Rayleigh fading, you should average data for a time period equal to the time it takes to traverse 40 wavelengths in your measurement vehicle and you should have no less than 36 to 50 points in that time. For the remainder of this text we will assume 40 points to make the calculations easier.

The biggest misconception with applying the 40-Lamba criteria to coverage measurements is that all measurements should be made with an averaging time exactly equal to 40-Lamda. While 40-Lamda is the minimum filtering that needs to be done to reject Rayleigh, it is not the most appropriate averaging time for coverage analysis. In almost all coverage analysis, the 40-Lamda averaged samples must be averaged further. Due to the accuracy and reporting rate of position measurement devices (GPS for instance) and the real practical problem of too much data this extra averaging is valid and necessary. Clearly, the averages of averages is just a longer average, and the resulting data no longer has an integration time of forty wavelengths.

That is not to say that the 40-Lamda criteria does not apply to coverage analysis. In fact it is very important. From the criteria, the minimum sampling rate is about once per wavelength at the fastest vehicle speed. At 800MHz, for example, a wavelength is about a foot. Using the 40-Lamda criteria, an initial sampling rate of 88 samples per second is needed to make measurements with a maximum drive speed of 60 mile per hour.

It is important to realize that Rayleigh fading is a spatial phenomenon not a time one. The averaging is actually intended to be done over a distance of forty wavelengths. Since most people performing coverage analysis average samples spatially after they are collected. That is to say, all the samples within a grid on a map are averaged to produce one point. To insure rejection of Rayleigh fading, the grid size must be larger than forty wavelengths. This in general is not a problem. At 800MHz, forty wavelengths is about 40 feet. Generally much larger grid sizes are used.

A Practical Example

A BVS Coyote receiver and Gator transmitter are going to be used to do pre-site survey at 800MHz. The Gator transmitter is hoisted up on a crane and the drivers are sent out to perform the drive study.

Since the Coyote receiver, in single channel mode, has an internal sampling rate of 512 samples per second regardless of internal averaging, we can calculate the maximum drive speed that is allowed. Since we want to have at least one sample per wavelength, as per 40-Lamda, the maximum speed would be 1ft*512/sec or 349 miles per hour! Obviously, the Coyote can be used for coverage analysis at any speed.
Since 512 points per second is far too much data to be processed, further data reduction is desired. The Coyote has internal filtering and decimation and the output rate can be reduced to 1 report a second. Each report is the average of all data received during that second, so we still have an initial sampling rate of 512 samples per second. This setting is the most convenient since the internal GPS receiver in the Coyote reports position once per second. At this point we have statistically correct data samples each with a position stamp.

The data should be spatially averaged in post processing. Since forty wavelengths is only forty feet at this frequency, almost any convenient grid size will do. Remember that the accuracy of GPS, with selective addition off, is only about 30 meters, so grid sizes larger than that would be appropriate. In expensive post processing software the grid size can be selected. When processing data yourself, it is often convenient to make the grid based on Latitude and Longitude from the GPS receiver. In the New York area, one degree of latitude is 69 miles and one degree of longitude is 50 miles. Therefore, averaging data with the first three decimal places the same would be an easy way of getting an appropriate grid size.

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