Uniden R1/R3 Advanced Mode Sensitivity Calculations

InsipidMonkey

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I was thinking about the recent discussions on what K band sensitivity to run in Advanced mode and the post by BRD/Vortex about the impact of each setting on detector sensitivity, and thought I would crunch the numbers myself. Not sure if anyone has bothered working this out before, a quick search didn't turn up anything.

Stop now if you don't care about the math, the moral of the story is the % sensitivity settings correlate with the expected difference in detection range.

I believe BRD posted this elsewhere already, but here ya go:

HWY
KA = Full sensitivity
K = Full sensitivity
X = Full sensitivity

CITY
KA = Full sensitivity
K = –15dB
X = –15dB

ADVANCED
- 100% = Full sensitivity
- 90% = –1dB
- 80% = –2dB
- 70% = –3dB
- 60% = –4.5dB
- 50% = –6dB
- 40% = –8dB
- 30% = –10.5dB
At first glance the sensitivity adjustments in Advanced seem somewhat arbitrary, differing by 1 dB as you start to decrease from 100%, and increasing to a 2.5 dB difference at the end. I knew the dB scale was logarithmic, but these numbers seemed rounded off enough that I wanted to calculate what the exact difference in expected detection range would be at each setting.


Looking at an equation for radar detector range, we see that the maximum range of a radar detector is inversely proportional to the square root of the detector sensitivity.
For example, see: copradar.com: Radar Range Equation


Radar Detector Range
Radar has a range loss inversely proportional to range to the 4th power (1/R[SUP]4[/SUP]). Radio communications range losses are inversely proportional to range squared (one-way path is 1/R[SUP]2[/SUP]). Signal power received (by a radar detector), where G[SIZE=-1]det[/SIZE] is detector antenna gain, can be expressed as shown below. By substituting radar detector minimum signal for power received, detector maximum range can be estimated if radar power and antenna gain are known (ERP -- effective radiated power).​
da9df8bfabb1fbbb5804911029e640a6.gif

P[SUB]det[/SUB] = Power Received by Detector
G[SUB]det[/SUB] = Detector Antenna Gain​
Radar propagation loss is proportional to 1/R[SUP]4[/SUP] (2-way signal path), while a radar detector would be picking up the signal on the direct (1-way) path with loss proportional to 1/R[SUP]2[/SUP] (a hugh advantage for the detector). Another hugh advantage is the radar is receiving a reflection (RCS), most of the reflective energy is directed away from the radar. The radar has the advantage of a much larger antenna (more gain) and more sensitive (to radar signal) receiver. However, good radar detector should be able to detect a radar before the radar detects the vehicle, but not always.​
Thus if everything else is constant (radar power, frequency, antenna gain), the difference in expected range between two sensitivity settings can be calculated by:

R/R[SUB]0[/SUB] = sqrt(S[SUB]0[/SUB]/S)​

Where the relative sensitivities must first be converted from the logarithmic decibel scale (yielding the relative sensitivities below), and taking the square root of this gives the relative detection range:
upload_2017-12-1_16-28-9.png

K band sensitivitydB change (logarithmic)Relative Sensitivity (S/S[SUB]0[/SUB])Relative Detection Range (R/R[SUB]0[/SUB])
100%0100.00%100.00%
90%-179.43%89.13%
80%-263.10%79.43%
70%-350.12%70.79%
60%-4.535.48%59.57%
50%-625.12%50.12%
40%-815.85%39.81%
30%-10.58.91%29.85%
City-153.16%17.78%

Thus the Advanced setting percentages actually correlate well with the calculated difference in ideal detection range assuming all other factors are equal. One interesting thing to note is that City mode (-15 dB) is the equivalent of an Advanced Mode setting of about 18% (e.g. 18% of the ideal range in Highway mode).
 
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Brainstorm69

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Very interesting that it looks like Uniden did their homework (as did you). Thanks for this!
 
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InsipidMonkey

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K-band - Mt Calm 45°
Ranked by distance of first detection:
59719.png
Just noticed that the 30% and City settings/calculations agree almost exactly with the TXCTG - Mt Calm K-Band test:

Calculated: Adv 30%: 29.85%, City: 17.78%

Tested: Adv 30%: 28.5%, City: 17.5%


Edit:
Since we're looking at the difference in maximum detection range (notice how everything is compared to the best run of TXLe's R3), the actual numbers are even closer if we only look at the best run at the reduced sensitivity settings:

Calculated: Adv 30%: 29.85%, City: 17.78%

Tested: Adv 30%: 4914/16971= 28.95%, City: 3025/16971= 17.82%
 
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Choose Life

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Extremely interesting
Thank you for this
 

wayne77

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This is great, thank you!
 

leesrt

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I have a question, why is it in testing it seems k band gets the most attention but on the highway Ka band is more predominant?
 

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I have a question, why is it in testing it seems k band gets the most attention but on the highway Ka band is more predominant?
Because Ka band on the R3 and R1 was tested extensively pre release May 2017 to July 2017
People are still doing Ka tests but we know it's solid on Ka all bands all the time
With K there are so many ways to tune and filter it's about getting max range with zero falses
 

Vortex

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This is awesome! I've been thinking about this and how the inverse square law factors into the percentage calculations and I must admit I'm a bit surprised to see everything add up so nicely. Thanks for running the numbers!
 

Gowski

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Very useful info, makes it so much easier now when using Adv mode knowing the sensitivity percentages match the relative detection range. Thank you!
 

Vehicle 1

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Interesting info, thanks for crunching the numbers for us!
I didn't realize how low the percentage is for city mode, I am experimenting in advance at 70-80% and although I still get some stationary falses it's pretty darn quiet around town. I'll try 60-50% next.
 

InsipidMonkey

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Made it sticky... Very useful info for R1/R3 owners...

Thank you [MENTION=13502]InsipidMonkey[/MENTION]
Thanks! I'm glad people are finding it useful. After seeing how closely the numbers worked out I assumed most wouldn't find it very interesting.
 

spongebobradarpants

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I'd like to comment here that, per my testing, if you see K or I/O K, it may not be a huge detriment to just run K at 50% or so if you live in an area with terrain that provides frequent, major choke points to detection, like sharp curves and elevation changes (hills). You may not get an inch more range on 100% vs 50%, but you'll certainly be less annoyed by BSMs. Just a thought. Use your best judgement.
 

warnerwh

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Thank you very much. I wondered how the numbers translated.
 

schissler

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per my testing, if you see K or I/O K, it may not be a huge detriment to just run K at 50%
I am going to disagree here.

Just did 5500 KM (3420 miles) round trip - Had about 5-6 K band encounters. Had my R3 down to 60% to reduce BSM...Had a pretty close call after I did that and this was wide open flat prairies in Saskatchewan.

By the time I took 2 secs to determine it may not be a BSM, let off the gas slightly, got full ramp 2-3 sec later, hit the brakes, got visual on LEO within another 2-3 secs...too close for comfort really.
 
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spongebobradarpants

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I am going to disagree here.

Just did 5500 KM (3420 miles) round trip - Had about 5-6 K band encounters. Had my R3 down to 60% to reduce BSM...Had a pretty close call after I did that and this was wide open flat prairies in Saskatchewan.

By the time I took 2 secs to determine it may not be a BSM, let off the gas slightly, got full ramp 2-3 sec later, hit the brakes, got visual on LEO within another 2-3 secs...too close for comfort really.
Look at my test and read my conclusion. I'm not going to argue with someone until they see what I'm talking about.
 

spongebobradarpants

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I dont need to.
I saw first hand how close of a call I had with it cranked down. It went right back up to 100% after that.
No see that's like saying "I hate Fiji" even if you've never read or heard anything about it in your entire life. You don't understand what I'm getting at unless you read my post. In my area choke points make local popo K detections the same whether you have a Cobra or a Uniden R3. It's still more than worth it to buy the detector for Ka range but in city mode some places won't benefit. Again, I'm not going to say anything else because I'm not going to argue.
 

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This is such a great comparison chart
 

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