Excel sheet to estimate range for Indoor and Outdoor

Hey,

This is cool stuff!! Once I did a test with two CC2540EM (using dipole antennas) and I got a range about 260m outdoors on an open field. Your tool approximates 104m, am I missing something or did I just got lucky when doing the measurement? :) Picture attached.

Edit: After looking more closely on the graph and knowing that CC2540 has -93dBm in sensitivity (High-Gain mode), I see that my measurement is backed up by Friis equation. Really useful tool here!!

Hi Joakim,

Thanks for the feedback.

Good to hear that the LOS results correlate.

This tool helps a lot especially when discussing indoor range and the impact of having a "dry wall" or "concrete" wall between the Tx and Rx units.  

Hello Joakim,

I appreciate your work..

but can you tell me is your tool support cc2538 chip also ? becoz i am using cc2538 and zstack HA 1.20 so how can i use your tool ?

thanks & regards,

Maneesh

CC2538 is included in the Rev1_03 version.

Regards, Richard

How does this work? I tried entering the same inputs as Joakim, but I got #N/A as a result in the write protected cells

Edit: I got it working by using "." as a decimal point instead of ",".

What is the typical gain for iOS devices and how could I enter in such a value? How do I select different absorbtion materials?

There is no typical gain value for an iOS device since this depends on the specific design of the antenna. For a typical gain value, I would keep this at 0 dB for 2.4 GHz.

Regards, Richard

Richard,

Your spreadsheet is very, very helpful.  Would you mind sharing the source of your wall energy absorption numbers?

Thank you,

--Jamie

Hi Jamie,

The source of the energy absorption numbers is from a report from the U.S. National Institute of Standards and Technology (NIST).

Regards, Richard

Hi Marc,

I can add the CC2564x parts in the drop down list in the next version.

For time being, just choose a radio /data rate setting that correlates to the sensitivity level specified by the CC2564x.

Regards, Richard

and I believe this video demos the longest CC1120+cc1190 RF link distance. Thumbs up RIchard!
www.youtube.com/watch

I did some line-of-sight tests between the TI CC2540 in a Panasonic PAN1720 module and an iPhone 6 and logged the reported RSSI on the iPhone and on the CC2540 as a function of distance.  The RSSI on the CC2540 in standard receiver sensitivity would clip at around -35 dBm but the iPhone would not clip so had usable results for very close proximity.  The following formula for the CC2540 fit very well with a coefficient of determination of 0.994 (the iPhone has a roughly similar formula but didn't fit quite as well at 0.989) where both devices were about 4 feet (3.3 m) above the ground.

RSSI = -22.9 * LOG10(distance in feet) - 38.7

and I found that the connection would drop or be very unstable when the RSSI got to -85 and especially below -90 which is roughly the noise level (from Wi-Fi diagnostics) and the receiver sensitivity is -87.  This translates into a (barely) usable distance of around 100 feet though -87 would give 130 feet.  Your spreadsheet with no guard band gives 156 meters or 512 feet which seems overly optimistic while using the 20 dB "Guard band without Antenna Diversity" may be OK for a very reliable link at 21 meters (69 feet).

Your RSSI vs. distance was roughly  the following:

1 meter --> -40 RSSI

3 meter --> -50 RSSI

10 meter --> -60 RSSI

25 meter --> -70 RSSI (ground model vertical polarization)

100 meter --> -80 RSSI

200 meter --> -90 RSSI

which if I convert to feet to compare to my formula I get the following as a fit for yours:

RSSI = -21.2 * LOG10(distance in feet) - 28.8

So it looks like your rolloff with distance is roughly similar but your offset overestimates the RSSI as being roughly 10 dBm higher for any given distance.  Any thoughts as to why there is this difference?

Latest version (1.14) has been updated to include:

• selected chip's blocking parameter (+/- 10 MHz) and how this effects range with an unwanted interference / jammer.
• environment noise floor parameter since this is becoming an important factor in several countries. 
• Mean Effective Gain of antennas (measurements from CC-Antenna-DK2) 

Any feedback is welcomed.

Regards, Richard

Latest version (1.16) has been updated to include:

• Changed guard band to link margin 
• Custom frequency, sensitivity and blocking level can be entered

Hello Joakim,

I also appreciate your work. Thank you very much for the Excel sheet.

It's going to depend on the antenna, but for the standard antenna as used in the CC2540 USB Evaluation module kit and in the PAN1720 module, I measured the free space RSSI and found the following (regression determined) formula to be reasonably accurate for +0 dBm output power: RSSI = -22.9 * log10(distance in feet) -38.7

Using your distances I get

1 meter as -50.5

3 meter as -61.4

10 meter as -73.4

I was generally able to connect if the RSSI was somewhat above the noise level, usually OK to around -80 dBm (sometimes to -85 dBm, but not reliably) so around 19.5 meters.

So basically I get similar results to what you are getting even though you are using the newer CC2640 chip.  That's the way it goes with BLE unless you use a better antenna.  You can easily get 10 to 15 dBm higher with a better antenna which would get you to 53 to 88 meters, but they are much larger than the chip antenna.  You can also use +4 dBm output power and higher receiver sensitivity for a little better range.

Richard,

great to find this updated tool - thank you.

Regards, Bernd