An Independent Review of the Intoxilyzer 9000
Part 3 - The Effects of Radio Frequency Interference
Counterpoint Volume 2; Issue 2 - Article 5 (September 2017)
An article in the Core Skills III-2 Module
Jan Semenoff, BA, EMA
Forensic Criminalist
The opportunity to conduct an independent analysis and performance review of a new breath alcohol testing device is rare, particularly the higher-end, evidentiary-level units. Access to these technologies is stringently controlled by both their manufacturers and the police and government agencies that control them. Additionally, state agencies are often reluctant to publish the results of their official assessments and analysis of the devices.
When given the opportunity to perform such a review on a new Intoxilyzer 9000, I designed a series of experiments to quickly analyze the overall performance of the device. I attended the device’s location with colleague Tom Workman (1948 - 2019) to determine its suitability and reliability in a number of key areas, including:
When given the opportunity to perform such a review on a new Intoxilyzer 9000, I designed a series of experiments to quickly analyze the overall performance of the device. I attended the device’s location with colleague Tom Workman (1948 - 2019) to determine its suitability and reliability in a number of key areas, including:
- Overall design and ease of use
- Accuracy in determining in vitro BrAC levels using a simulator
- The ability of the device to determine the presence of Fresh Mouth Alcohol using a Residual Alcohol Detection System (RADS) or the so-called “slope detector”
- Reliability in reporting BrAC readings that are highly specific to ethanol - See the article: Specificity
- The effect of Radio Frequency Interference on the device
This article will examine the capacity of the device to detect Radio Frequency Interference. Part one provided a general overview of the performance characteristics of the Intoxilyzer 9000, looked at the apparent accuracy of the device using simulator readings, and examined the ability of the device to “flag” false-positive readings caused by fresh mouth alcohol contamination. Part two examined the unit’s specificity towards ethanol detection, and its ability to identify the presence of an interferent chemical
An important caveat:
This assessment on an individual Intoxilyzer 9000 was done in circumstances of complete access to the device, but under limited time constraints. Simply put, we did not have the time necessary to run exhaustive testing on the 9000 to generate the raw data necessary to ensure a proper statistical analysis. Over a ten-hour period, we were able to run about 60 individual tests on the 9000, and inspect its interior and component parts. We need further access to these devices to draw meaningful conclusions.
As an editorial position, Counterpoint, calls on the manufacturers of ALL breath test instruments, and all government agencies that operate and control them, to make these devices, used in criminal proceedings as evidentiary collection devices, available for independent review and analysis. Transparency regarding both the physical and software design, their manufacture, and the maintenance and operation of the devices is critical in maintaining a degree of openness and trust towards the numerical BrAC results generated.
This assessment on an individual Intoxilyzer 9000 was done in circumstances of complete access to the device, but under limited time constraints. Simply put, we did not have the time necessary to run exhaustive testing on the 9000 to generate the raw data necessary to ensure a proper statistical analysis. Over a ten-hour period, we were able to run about 60 individual tests on the 9000, and inspect its interior and component parts. We need further access to these devices to draw meaningful conclusions.
As an editorial position, Counterpoint, calls on the manufacturers of ALL breath test instruments, and all government agencies that operate and control them, to make these devices, used in criminal proceedings as evidentiary collection devices, available for independent review and analysis. Transparency regarding both the physical and software design, their manufacture, and the maintenance and operation of the devices is critical in maintaining a degree of openness and trust towards the numerical BrAC results generated.
The Intoxilyzer 9000:
The effects of radio frequency interference
We have examined the Intoxilyzer 9000 in four prior Counterpoint articles:
Article: Reference:
The New Intoxilyzer 9000 Archived
The Intoxilyzer 9000 & the Unknown Archived
The Intoxilyzer 9000 & Residual Mouth Alcohol Detection Volume 2, Issue 2; Article 3
The Intoxilyzer 9000 & Specificity Towards Ethanol Detection Volume 2, Issue 2; Article 4
Article: Reference:
The New Intoxilyzer 9000 Archived
The Intoxilyzer 9000 & the Unknown Archived
The Intoxilyzer 9000 & Residual Mouth Alcohol Detection Volume 2, Issue 2; Article 3
The Intoxilyzer 9000 & Specificity Towards Ethanol Detection Volume 2, Issue 2; Article 4
What is Radio Frequency Interference (RFI) ?
Radio Frequency Interference (RFI), also called Electromagnetic Interference (EMI) occurs when an electrical disturbance is generated on an electronic device by an external electrical source. This source may affect electronic or electrical circuitry and degrade or otherwise impede the performance of the circuit affected. The effects can include data corruption, an increase in error rate, total or partial data loss, and may even go so far as to stop the affected device from functioning altogether [1].
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[1] In an extreme example, EMI pulses are used in electronic warfare to interrupt communications and computer technology of enemy combatants.
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In our modern and increasingly connected world, the use of radio transmission and receiving devices is ubiquitous, and today certainly more so than just a few years ago. When modern police breath alcohol testing devices were invented, no one conceived of high speed, Wi-Fi enabled, 5G devices used regularly to access a continuous stream of Internet data, text messages and voice communications. Few could have foreseen a world where powerful, interconnected electronic devices were so small, that not only do they easily fit in the palm of your hand, but we lose them in our own homes (along with our car keys).
A quick peek at the Wi-Fi networks available locally to my computer indicates that about 20 different signal sources are in my immediate vicinity. Additionally, cellular phones, smart devices such as tablets or other Wi-Fi enabled devices (now including everything from Blu-Ray players to “smart” refrigerators), and other Bluetooth devices are all emanating their digital transmissions, regardless of whether they are on an active call or not. This background “noise” can create the situation generally associated with RFI and EMI emissions.
Figure 1 - Potential sources of Radio Frequency Interference include personal electronics, such as cell phones, smartphones and Bluetooth headsets; Police equipment, including radios, cellphones, and laptops or Body Worn Cameras that transmit wirelessly, and; Wireless LAN (WLAN) devices in the police station that set up the local area wireless network, if any.
To compound the problem in police evidentiary breath testing, we have such sources as the cellphones of the people in the vicinity, police portable radios, and now, police body-worn cameras and wireless laptop computers, all transmitting notification signals back to their respective sources, telling the electronic Internet (and local intranet) world, “I am here…”
Keep in mind that you do NOT need to be actively transmitting a voice or text message for the RFI signals to be generated.
A problematic means of assessing the RFI detect circuitry:I have frequently heard forensic criminalists and state crime lab chemists or technicians describe in court how they assess the reliability of the RFI detect during routine annual maintenance of breath alcohol testing devices. Typically, a police radio, or similar transmitter, is placed near the device in question during its “active phase” [2] of breath sampling. The radio is then “keyed” into the active transmission mode, and the response of the breath test device recorded. However, this assessment is different from the Internet, cell phone, Wi-Fi, Bluetooth enabled world I’ve just described.
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Modern police radios are part of an integrated communication system offering multiple channels or workgroups, radio and telephone integration and location and GPS services.
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[2] I’m separating here the idea of an active mode in the breath testing device (it is ready to receive, or has been activated to receive breath samples) as opposed to its passive mode (where it is in the “stand-by” position, waiting for some activity to occur – i.e.; Push the START button).
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The problem with assessing the impact of RFI is that it is generated in an intermittent fashion, producing random and potentially irreproducible results. Indeed, the simple act of detecting the presence of RFI is a considerable challenge. As such, it has been frequently suggested that the prudent course of action is to limit exposure of RFI to devices that must deliver precise measurements with a high degree of reliability, or in critical-application situations. That is why we are required to turn our cellphones off, or into “airplane” mode, when we board a commercial flight, enter the ICU to visit a sick relative, or are in the vicinity of sensitive medical monitors and scientific measuring devices. |
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It should be noted that the RFI detector built into the Intoxilyzer 5000 and 8000 series of breath alcohol testing devices is based on technology of circa 1980-2000. Although the Intoxilyzer line itself has undergone various upgrades in their capabilities, the RFI detector circuitry they employ have remained essentially the same for these earlier devices since their creation about thirty years ago. They were designed to detect the presence of radio frequencies in the 10-300 Megahertz (MHz) range, as was commonly found in police radios of that era. Due to the increased performance of newer communication technologies, most of those radio devices have long been abandoned.
Modern police radios commonly transmit and receive within frequencies between 400 MHz to 3 Gigahertz (GHz). Cellular telephone voice and data technology used in the United States and Canada utilizes radio frequencies in the 800 MHz through 1.9 GHz range. Additionally, voice and data transceivers utilizing technology commonly known as “Bluetooth devices” operate in the 2.4 GHz range. Modern commercially available “walkie-talkies” operating in the FCC Licensed Family Radio Service bands operate in the 462-467 MHz range. |
A police radio from circa 1980 - The Motorola MX 350.
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The effect of these radio frequencies on the internal operation of breath test devices that use electronic circuitry similar to that of early computers is in debate. Accordingly, standard police procedures have been established in most jurisdictions in North America and Europe that prohibit the presence of active police radios, cellular telephones, and similar devices in breath test facilities.
This prohibition amongst police agencies is not unique. Most hospitals have policies prohibiting the use of similar radio or other electronic devices in patient care areas, where critical life-support or patient monitoring equipment is in operation. RFI interference to devices such as ventilators, patient monitors, pacemakers, neonatal incubators, motorized wheelchairs, and anesthesia delivery equipment has been reported and documented.
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The hidden danger of RFI:Although there has only been one reported case of an air crash where the use of cellular telephones has been alternately purported as responsible[3], the United States Federal Communication Commission bans the use of cellular phones in aircraft entirely (per 47 C.F.R. § 22.925). Similar bans are enforced in many other jurisdictions worldwide. It should be noted that newer cellular telephones transmit intermittent digital identification signals, whether an active call is in progress or not, so that local cellular transceiver sites recognize the mere presence of the phone for reception of incoming calls. As this function is beyond the control of the operator of the device, deactivating the device to the off position or “airplane” mode is warranted.
[3] Crossair Flight LX498, January 10, 2000 (flight from Switzerland to Germany). The official crash report does not mention cell phone activity as a primary cause of the crash, and instead attributes it to pilot error. However, a separate investigation into the cause of the crash documented that the autopilot system malfunctioned at the exact moment that one passenger's cell phone on board the plane received an SMS message, and another cellular phone received a call. After this information was made public, a number of countries that had previously been reluctant to do so outlawed cell phones on flights. The bans remain in effect to this day. |
In 1983, shortly after the introduction of the types of technology used by the Intoxilyzer and similar breath test devices into general police service, the National Bureau of Standards conducted a study (“Effects of Electromagnetic Fields on Evidential Breath Testers”, 1983) and concluded that the possibility of erroneous Blood Alcohol Concentration (BAC) readings, influenced by various radio frequencies, was “severe”. There are numerous reported, albeit anecdotal, instances where elevated BAC readings have been observed due to the presence of known radio transmissions. The problem, frankly, in extrapolating from these observed instances, is the unpredictability and lack of reproducibility of the circumstances that apparently gave rise to the elevated BACs. As such, the cautious and prudent approach is to absolutely eliminate the possibility of RFI altogether.
So, ultimately, the questions are:
- How does the Intoxilyzer 9000 Radio Frequency Detection circuitry identify the presence, if any, of interfering electromagnetic signals?
- Can RFI affect breath test results on the Intoxilyzer 9000?
Testing RFI effects on the Intoxilyzer 9000
Testing protocol:
In order to test the effects, if any, of radio frequency interference from cellular phone calls during an active breath test, we utilized two cellphones, calling one another in the general vicinity of the Intoxilyzer 9000, to create an active cellular transmission in progress. Both were Apple iPhone 6 phones, one operating on the Verizon network, the other roaming on the AT&T network. Breath tests were conducted with a zero BrAC test subject, and tests on a test subject with a known BrAC of 0.012 grams/dL.
Results obtained:
The results are as follows:
Figure 2 - Results obtained with RFI (Cellular signals) near an Intoxilyzer 9000
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With a zero BAC test subject, the 9000 correctly reported a zero BAC reading, but only identified the presence of the active cellular calls on 2/5 occasions. In order to generate the RFI message, one of the cellular phones, on an active call, had to be placed within 2 inches (6 cm) of the external antennae. Any distance further than 2” would not generate an RFI DETECTED message.
In the next tests, the active cellular phone was placed within a 5-inch radius of the antennae while a test subject with a “true” BAC of 0.012 grams/dL provided breath samples. The BrAC level was measured, initially from the Intoxilyzer 9000 itself, and verified using a recently calibrated handheld device (an Intoximeter FST). Our results were dismaying: With the active cellular calls under way, the 9000 provided two back-to-back readings of Zero and 0.026 grams/dL, both without indicating the presence of any RFI.
Limited time prevented us from obtaining further results.
With a zero BAC test subject, the 9000 correctly reported a zero BAC reading, but only identified the presence of the active cellular calls on 2/5 occasions. In order to generate the RFI message, one of the cellular phones, on an active call, had to be placed within 2 inches (6 cm) of the external antennae. Any distance further than 2” would not generate an RFI DETECTED message.
In the next tests, the active cellular phone was placed within a 5-inch radius of the antennae while a test subject with a “true” BAC of 0.012 grams/dL provided breath samples. The BrAC level was measured, initially from the Intoxilyzer 9000 itself, and verified using a recently calibrated handheld device (an Intoximeter FST). Our results were dismaying: With the active cellular calls under way, the 9000 provided two back-to-back readings of Zero and 0.026 grams/dL, both without indicating the presence of any RFI.
Limited time prevented us from obtaining further results.
RFI detect circuitry - Under the hood:
A peek at the internal RFI detection circuitry in the Intoxilyzer 9000:
Figure 3 - From the main board on the 9000, a set of 8 wires is bussed to an "RFI Detect Board"
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Figure 4 - The 8-wire bus from the main board plugs into the RFI Detect Board. Note the flexible connector leading to the external antenna itself (ANT IN), top.
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With the active cellular calls under way, the 9000 provided two back-to-back readings of Zero and 0.026 grams/dL, both without indicating the presence of any RFI. The test subject had a "true" BrAC of 0.012g/dL.
Figure 5 - The antenna lead (from Figure 4, top) is a flexible plastic circuit connector with three wires that runs underneath the CMI sticker on the left side of the 9000. Our tests indicated that a cellular phone, transmitting a voice signal in an active call, had to be placed within about 6cm (2 inches) of the CMI sticker/antenna location to generate an RFI DETECT message. It appears that this is the ONLY antenna location on the 9000. There were no leads from the main board antenna port, or antenna board, to the external heated sampling hose, also shown here.
Overall impression on the 9000 RFI Detect abilities
Obtaining proper samples & operational implications:
Relying upon the RFI detect circuitry to determine the presence of stray radio waves is insufficient. It appears that the source of any potential interference had to be within a radius of about two inches from the external antennae to be detected. It also appears that with an actual BrAC measurement (0.012 g/dL), the readings obtained may have been affected by RFI, both generating false-negative (Zero) and false-positive (0.026 g/dL) readings, without reporting the detection of any RFI present.
As previously stated, this assessment on the Intoxilyzer 9000 was done under circumstances of complete access, but was time limited. Simply put, we did not have the time necessary to run exhaustive testing on the device to generate the raw data necessary to make a proper statistical analysis. We need further inquiry to draw meaningful conclusions.
Final thoughts:
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With albeit limited tests (seven) we see preliminary indications that the Intoxilyzer 9000 does not adequately detect the presence of RFI, and additionally, that the RFI may adversely affect the reported BrAC results. Therefore, the only prudent course of action is to eliminate all potential sources of RFI. This means turning off police radios, cell phones or smartphones of both officers and test subjects, police body cams, laptops that are transmitting, and any Wi-Fi devices, etc. The intermittent nature of RFI, and its potential effects, dictates the need to remove any potential source of EMI and RFI altogether.
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Furthermore, a proper deprivation and observation period, both before and between the breath samples, coupled with the use of replicate testing (with close sample agreement) will help to establish the reliability of breath alcohol testing results.
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Send me your questions or comments:
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For further study:
- Dubowski, K.M., Acceptable Practices for Evidential Breath-Alcohol Testing, Center for Studies of Law in Action, Borkenstein Course Materials, Indiana University, May 2008.
- Palmentier, J-P., Woodall, K., and Savoia, C., Radio Frequency Interference Messages During Breath Testing of Suspected Impaired Drivers Using the Intoxilyzer® 5000C: A 13-Year Retrospective Analysis, Canadian Society of Forensic Science Journal, 2016, Vol. 49, No. 3, 127-137.
- Unknown Author(s), “Effects of Electromagnetic Fields on Evidential Breath Testers”, National Bureau of Standards, 1983.
