Hello, all! Just a quick question regarding output power. For Canada/US, on the 2.4GHz band, what is the maximum power output I can configure the radio to operate at? I see some references in the datasheet to about 19.7dBm, but that may just be the power level that they tested at for certification. Thanks!
Well, here’s a clip from the Pro 5G’s datasheet:
I’m not sure of your particular interest in TX power but I’d respectfully note that there are numerous other variables to be considered vis-a-vis wi-fi performance other than AP TX power, e.g., power budget (the settings of the other device and the gain of its antenna), interference, log-normal fading, path obstruction, multi-path, channel width, modulation scheme, etc.
So, if your question is as simple as it is presented (i.e., clarification of the spec,) sorry for the “over-answer.” ;<) If there are follow-on questions let us know – someone here will answer.
BTW – the Pro 5G’s wi-fi is excellent – I don’t go far from home without mine. ;<)
Thanks very much! The inquiry comes as a result of needing to test & qualify this radio for a product it will be integrated with. We need to make sure that we are complying with FCC regulations and not exceeding any emitted power limits when we add our antenna, etc. If it is capable of exceeding limits then we need to know so we can configure it appropriately and warn the end-user in documentation about not exceeding our factory settings.
In the next day or two we’ll have a network analyzer and power meter in house to test actual radiated power. So I suppose that’ll answer things for us as well!
you can turn on boost but it does warn you : Output power may exceed local regulatory limits
As for the limits that depends on where you live. Even with boost on the limit isn’t met where i’m at. Canada i’m not sure. I do know some areas have pretty strict rules (local) - check out Greenbank, WV
The product would have had to be FCC approved before it could be sold in the USA. If you remove the OEM antennas and add your own I’d calculate the power like this: TX power (dBm) - antenna gain of the antennas removed + gain of new antenna - transmission line losses (dB and obtained from the manufacturer’s specs.) Connector losses are generally negligible when good products are used and they’re properly applied.
You’re being very diligent in this. If you are not using directional antennas it is highly unlikely you will exceed FCC limits. I’d be interested to see how the calcs stack up against actual measurements. :<)
We connected our network analyzer and tested the 2.4GHz output. Sadly we weren’t able to test the 5GHz bands because the NA doesn’t go that high.
To test, we connected one output to an antenna and the other output to the NA. The connection was made through a 30db attenuator. We used “Channel Power” mode on the network analyzer and set it to a 40MHz width. And we characterized the losses in our test cables. We then enabled just the 2.4GHz radio, set it to a specific channel, and used the custom power setting to choose a specific output power (3-30dBm). Region was set to USA.
We found that the output tracks quite linearly up to 15dBm. So if we set it to 10dBm, we’d measure -20dBm (10-30= -20). However beyond 15, things got a little squirrely. At a setting of 20dBm output, we would only measure about 17. The maximum output using either a 30dBm setting or “Fixed Max + Boost” was about 18dBm.
We also found that the output power varied depending on the output we tested. The Wifi A output was was not able to produce quite as much power as B on out test unit, reaching a maximum of 16.5dBm.
Finally, we were confused by the fact that the channel never seemed to actually occupy the full 40MHz that we had set. Regardless of whether we chose 20MHz width or 40MHz, we consistently saw a curve that was just 20MHz wide.
It’s possible that our measuring methods were off and that there’s more going on. But the radio we have sure doesn’t seem to be able to produce anywhere close to 23dBm. And I’d love an explanation for the 20/40MHz bandwidth discrepancy we’re seeing! Our next test will be with a power splitter, where we’ll tap the output just before the antenna to see if we can collect more accurate data.
Hi Jeff. I may have a partial answer for you but I too am curious to how some of your findings can be explained. Perhaps @WeiMing or one of his colleagues could consult with Peplink’s engineers and get us an answer?
Thanks, @Rick-DC, will pick up from here.
@jschmidt probably you can submit a ticket so I can link up the Engineering Team to further look into it?
You may quote this forum link in the ticket via the highlighted option when creating a ticket.
Thanks! Our tests are still ongoing as we wait for more test equipment to arrive. Once they’re complete, and if we’re not getting the results we expected, I’ll be sure to file a ticket!