Aware Electronics looks at BlackCat Systems and GeigerGraph Software


Using Monitors With The Same Type Tube, Aware Electronics Software Can Measure Radiation Levels Ten Times Higher Than BlackCat's System or Any Monitor Using GeigerGraph Software


Note if you desire to use any of Aware's RMs including the RM-60, RM-70, RM-80 or RM-G90 with BlackCat Systems software for Apple's MAC or BlackCat's Windows version, follow these instructions:

There are four leads from the RM-60, RM-70, RM-80, RM-G90, C-Box, etc. that connect to the four middle connections of the MOD jack on the side of the RM or C-Box:

Holding the RM or C-Box and looking into the MOD jack with the tab-slot at the top, leads are from left to right:

Minus
Plus
Signal
Signal ground

Wire up a 9 pin RS232 adapter for use with a serial port or serial to USB adapter as follows:

RS-232 pin 3 to Minus
RS-232 pin 4 to Plus
RS-232 pin 2 to Signal

Aware has available pre-wired adapters that accept the four conductor wire with MOD plug from our RMs, and plugs into a standard 9 pin RS232 serial port as found on PCs and USB to serial adapters which allows use of our RMs with BlackCat software. To order "BlackCat Adapter" $5.00


We tested BlackCat Systems radiation monitoring software which uses the same technique to count radiation pulses as many other radiation software packages, including GeigerGraph and GeigerGraph for Networks.

BlackCat uses an interface between the radiation monitor and the PC that we considered long ago but rejected. It consists as follows. The radiation monitor generates a positive going pulse with each detection. This pulse is connected by cable to the RX (receive) pin in the PC's serial port. The cable also connects the radiation monitor's ground to the serial port's ground.

The PC software opens the serial port for communication, 38,400 to 57,600 baud, 8 data bits, and one stop bit. When a pulse arrives at the serial port, the serial port's UART interprets it as a start bit. The positive pulse must go negative, or to ground, before the time a normal character would be received such that the UART interprets it as a stop bit. Otherwise the UART and its driver will throw a communication error. The software counts the number of bytes received per unit time and then reports the results.

57600 baud is 5760 bytes per second (10 bits per byte i.e. one start bit, 8 data bits and one stop bit) so the absolute maximum rate that could be measured using this technique is 5760 CPS but only if the stream of pulses are exactly aligned and perfectly spaced. In practice the maximum count rate recordable would be less than 50%, i.e. less than 2800 CPS, due to the random nature of the pulses from the radiation monitor. (This is a well characterized phenomenon i.e. the maximum count rate of evenly spaced pulses a counter can detect must be at least twice as high as the expected count rate from a random pulse stream ).

57600 baud = 17.36 microseconds per bit. One start bit and 8 data bits = 156.25 microseconds so the pulse from the radiation monitor must be longer than 17.36 microseconds and less than 156.25 microseconds, even with low count rates. Otherwise the UART will throw a communications error thereby corrupting the count rate data. In addition, if any pulse arrives before ~200 microseconds, it could confuse the UART, for example by arriving at the time the UART expects a stop bit, which would then throw a communications error resulting in a corruption of the data.

To test the BlackCat software, we downloaded the most recent version (August 9th 2012). We connected the output of a precision pulse generator (Global Specialists) to the RX input pin of a PCI serial port (a standard high speed serial port) and the pulse generator's ground to the serial port's ground. We set the 5 volt square wave positive going pulse width to exactly 20 microseconds which is the pulse width BlackCat says is output from their radiation monitors.

During the test, we varied the pulse rate between 1 pulse per second to 7944 pulses per second by way of the pulse generator's pulse spacing control. All parameters including pulse width and pulse spacing were checked with a Hitachi oscilloscope. This represents the absolute best conditions for the BlackCat software with a precisely sized square wave pulse with exactly equal pulse spacing.

We carried out tests as above and also tests as above with the pulse generator's output connected also to the input of one of our LCD-90 inputs which is internally connected to the LCD-90's high speed CMOS counter chip. We configured the LCD-90 as a high speed (greater than 12 megahertz) frequency counter (zero dead time, 1 second time base unit) and ran a copy of our Aw-Radw software configured to receive from the LCD-90, once a second, the CRC error correction data packet from the LCD-90. Aw-Radw's "Summary Window" shows the exact CPS reading, updated once per second and these matched precisely the settings on the pulse generator as-well-as the data from the Hitachi oscilloscope.

During the tests we recorded the PC's screen to a wav file using MicroSoft's Expression which is displayed below. The results of the test were always exactly the same, with or without the connected LCD-90 and Aw-Radw display and with or without MicroSoft's Expression program running. The PC is a 2+Ghz dual core machine with 4 gigs of memory.

We also ran the exact same type test but with our Aw-Radw collecting and displaying the pulse rate data instead of the BlackCat software. In this case instead of connecting the output of the pulse generator to the serial port's RX pin, we connected it to the serial port's RI pin which Aw-Radw uses to generate an interrupt which causes Aw-Radw's highly efficient machine code optimized interrupt handler to increment a variable then immediately return from the interrupt. This technique completely by-passes the serial port's UART and allows Aw-Radw to count pulses from the serial port in excess of 50,000 CPS regardless of the serial port's UART settings. With the pulse width set to 20 microseconds as per the BlackCat tests, the maximum possible count rate is ~25,000CPS due to the width of the pulse and this is the value reported by Aw-Radw when counting pulses connected to the serial port's RI line. With shorter pulse widths, the maximum count rate is higher, and in this case, Aw-Radw can count pulses coming into the serial port's RI line in excess of 50,000 CPS. As indicated above, when using our USB-MSP or LCD-90, Aw-Radw can report count rates in excess of 12 million CPS.

The following wav file shows the test in progress: BlackCat Test Video

Results from the test:

Pulse Rate - BlackCat Reports - % Deviation Error

1 CPS-------------2 CPS-------------100% high error
10 CPS------------9 CPS-------------10% low error
96 CPS-----------81 CPS-------------15.6% low error
982 CPS---------818 CPS-------------16.7% low error
1037 CPS--------865 CPS-------------16.6% low error
1614 CPS-------1334 CPS-------------17.35% low error
6291 CPS-------3974 CPS-------------36.83% low error
7962 CPS-------3307 CPS-------------58.47% low error

If the pulse stream was not highly optimized with exact evenly spaced pulses but rather a randomly spaced series of pulses as occurs with a radiation source, one would expect errors at least 100% higher than those shown above 2500 CPS i.e. with a random pulse stream with a rate of 2500 CPS, the BlackCat software would report ~1250 CPS, 50% less than the actual due to the baud rate limitation and random nature of the pulses. Note in other areas of BlackCat's website he indicates the use of 38,400 baud with a pulse width of 100 microseconds which would vastly increase the errors. In this link, BlackCat seems to indicates 100 microsecond pulse width BlackCat Systems Interface

Near the end of the video, we demonstrate how clicking on any BlackCat software window seems to freeze the update of the count rate and then after returning Windows focus to BlackCat's main window, it advances the time with a wildly high CPS rate near 25,000 CPS then back down to its 58% low error. This serious defect occurs even at low count rates and with various conditions. For example just holding the mouse button down while the pointer is over BlackCat's window title bar freezes the updates until the mouse button is released. Other conditions can cause this defect to be triggered. Even several wildly high count rates in a row can occur. If one triggers this defect long enough, the BlackCat software will report wild rates higher than 2 million CPS.

2 million count

These defective rates are dutifully reported in the BlackCat's data output file exactly as they appear on its main window. This type of defect is completely absent from Aware's Aw-Radw software.

If you look at the count rate versus dose rate for the tube used in BlackCat's monitor (see image below), you can see its recommended operating range is up to 12,000 CPS but from 2500 CPS on up the BlackCat software would report a vastly lower count rate. This not only limits the abilities of the tube to less than 20% of its capabilities but also allows the highly hazardous situation were rising radiation levels beyond a certain point will be reported as a rate much lower than the actual rate and as the real rate increases beyond this point, BlackCat software will report a lowering rate i.e. the user would think the radiation level is dropping when actually it is rising.

Cs137 Sensitivity Graph

Cs137 Sensitivity

Most all of Aware Electronics Corp.'s competition uses the exact same technique for counting pulses as the BlackCat software does, including GeigerGraph and GeigerGraph Network and they also suffer from the same serious errors. These errors would be vastly increased if one used a USB to virtual serial port adapter instead of a real serial port with a real UART.

BlackCat Software, GeigerGraph, GeigerGraph for Networks: Serious Errors above 2500 CPS

Aware Electronics Aw-Radw with monitor directly connected to Serial Port: No Error up to 25,000 CPS. Maximum count rate ~50,000 CPS

Aware Electronics Aw-Radw with USB-MSP or LCD-90: No errors up to 12 million CPS

We did not purchase a copy of GeigerGraph software but we found a demo of it on youtube that reveals the same type error as discussed above: GeigerGraph Video


First image shows two Americium 241 discs generate 4200 CPS

geigergraph1.jpg

Second image shows GeigerGraph reporting 2360 CPS (141,575 CPM / 60) which is 43.8% lower than the actual rate of 4200 CPS. This is a much worse error than our tests of the BlackCat software with pulse generator due to the random nature of the pulses.

geigergraph2.jpg

Third image shows GeigerGraph with both Americium 241 discs and then with one disc. Note the plot with one is not equal to 50% of the plot with two but even with one disc, GeigerGraph is reporting a much lower count rate than the real count rate. This plot starts with a wild excursion to 310,000 CPM then levels out to 141,575

geigergraph3.jpg


A Note About The Actual Radiation Monitors

All Aware Electronics monitors use a technique of pulse detection from the Geiger tube to the PC, USB-MSP or LCD-90, that allows a count rate much higher than one would expect from the tube specifications supplied by the tube manufacturer. For example our RM-60 uses the same tube as the BlackCat GM-10, an LND 712. As indicated above and as seen in the Cs137 Sensitivity Graph above, the tube specs. indicate a maximum count rate of ~12,000 CPS. An Aware RM-60 with LND 712 tube feeding a standard serial port with standard software running on a standard PC was tested several years ago by the Dept. of Homeland Security. They exposed the RM-60 to a rising radiation flux finally reaching 2 million microR/hr. (2R/hr) gamma field. The RM-60 and software continued to report rising radiation levels up to the reported 2 million microR/hr. According to the tube response graph supplied by the manufacturer, the tube should only be able to report maximum levels of ~ 690,000 microR/hr (0.69R/hr.), not 2 million microR/hr. For information about Geiger tubes and high count rates, see this unclassified document: High Counting Rates Also see: The increased sensitivity of the RM-80 and its immunity from saturation

As regards power consumption, all Aware Electronics Corp. radiation monitors can operate with voltages ranging from 2VDC to 20VDC. Power draw at background radiation levels is ~0.08ma and climbs modestly to a few milliamps at very high radiation levels. The high voltage section is rigidly regulated, noise free and as indicated can operate with input voltages ranging from 2VDC to 20VDC. We noticed on BlackCat’s website a mention of the need for 9VDC at ~9ma which is a power draw ~90 to ~400 times higher than Aware’s monitors.

Aware Electronics monitors include an exclusive discriminator which, as indicated above, allows the accurate display of radiation levels well in excessive of what one would expect given the tube data sheet. When developing the circuit, we designed and tested several hundred variations and finally settled on the best performing. All active components are rugged silicon devices very resistant to radiation and burn-out. The resulting design represents an entirely original circuit available exclusively in Aware’s monitors.


To Summarize

BlackCat's GM-10 with software, and any other monitor using GeigerGraph and GeigerGraph Networks packages under ideal conditions (real serial port with high speed UART, no moving and clicking of the mouse, no opening of any other windows, etc.) maximum count rate less than 2,500 CPS. Otherwise very misleading and hazardous reporting.

Aware's RM-60 (as well as all our other monitors) with Aw-Radw software maximum count rate greater than 33,000 CPS, more than 10 times higher than BlackCat's and the other systems, with no errors and with moving of windows, with moving the mouse, clicking, etc.

In addition Aware's software, as-well-as Aware's LCD-90 and USB-MSP include sophisticated and exclusive dead time correction features settable in one microsecond increments which allows dialing in accurate readings under very high radiation levels.


A Note About Random Number Generation

Aware's software includes a very advanced random number generator for those interested in true random numbers. We use the unpredictability of the arriving radiation induced pulse which triggers an interrupt as part of our technique. As indicated above, our technique completely bypasses the serial port's UART.

Other competitors quickly added a random number generator to their software as did BlackCat. The problem with their system is they feed the pulse stream through the serial port's UART which is synchronized to the serial clock generator i.e. the actual interrupt is synchronized by the UART and therefore cannot be truly random as is Aware's technique. Aware's random number generator has been thoroughly tested by outside sources including a battery of DieHard tests showing the true random nature of our random data stream.


A Note About Coincidence Counting

Many years ago Aware Electronics designed and began manufacturing a coincidence detector box which uses an exclusive, highly accurate circuit. Shortly thereafter others, including BlackCat, added coincidence detection methods to their lineup. We are not sure what their circuit is based on but if it has anything to do with triggering counts through UART RX lines then it will suffer from the serial clock generator i.e. the actual interrupts will be synchronized by the UART(s) to the serial clock generator.

Someone at Aware Electronics got the simple idea that a coincidence circuit (C-box) connected to two RM-60s could be used to detect cosmic rays



The Good News:Any Radiation Monitor That Relies on BlackCat or GeigerGraph Software Can Be Adapted For Use With Aw-Radw, USB-MSP and/or LCD-90

With a very simple wiring modification (connect the radiation pulse line to the RI pin instead of RX pin) one can use Aware Electronics software package Aw-Radw with any monitor made by others that works with BlackCat or GeigerGraph software and enjoy bug free and extremely flexible recording, graphing and automatic FTPing to servers of radiation data and graphs with radiation levels up to 10 times higher than otherwise would be possible, without the prospect of the exceedingly hazardous situation of rising radiation levels being displayed as falling radiation levels.

Likewise any of these other monitors can easily be connected to Aware’s USB-MSP and/or LCD-90.

  • Aw-Radw Information
  • USB-MSP Information
  • About Aware's New LCD-90 Micro-Controller Data-Logger

    Contact Aware Electronics for more information: Aware@aw-el.com

    For the highest performance, which takes advantage of the techniques as detailed above under "A Note About The Actual Radiation Monitors" one should use one of Aware’s radiation monitors.


    Also See:

  • Comparison of Aware Electronics Corp. LCD-90 + RM-80 to the Inspector EXP Probe Model

  • Aware Electronics Radiation Monitors Independent Tests (Aware Electronics exclusive radiation monitor design provides detection capabilities 1000 Times Higher than many of our competitors)

  • Aware Electronics RM-60 Versus Digilert

  • A look at SparkFun Geiger Counter

  • Our exclusive interface and design
    Aware Electronics Corp. has been in the business of manufacturing radiation monitors and writing software for them since the late 1980s. Over that time we have perfected many aspects of the radiation monitors as-well-as the software.

    A gal at LND who we have known now for over twenty years told us everyone and their uncle are coming out of the woodwork to become new found Geiger counter manufacturers. She said "Even shoe makers have become Geiger counter makers". This page attempts to illuminate the hazardous nature of many of these new found products particularly in moderately elevated and higher radiation fields wherein readings can show dropping radiation levels when in reality they are rising.


    Aware Electronics Corp. Twenty plus years perfecting radiation monitors and software
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