Estimate environmental RF noise floor

I'd like to learn more about LoRa so I decided to build a few nodes but I'm unsure whether to use 433 or 868 MHz. TTN uses 868 MHz due to the excessive man-made noise in the 433MHz band due to alarms, cars, weather stations, etc.

Can I use an inexpensive 433MHz receiver (pic) to evaluate the noise level in my local area? If so, do I need to amplify the noise coming from the receiver with an OpAmp?

SeaWalker:
I'd like to learn more about LoRa so I decided to build a few nodes but I'm unsure whether to use 433 or 868 MHz. TTN uses 868 MHz due to the excessive man-made noise in the 433MHz band due to alarms, cars, weather stations, etc.

Can I use an inexpensive 433MHz receiver (pic) to evaluate the noise level in my local area? If so, do I need to amplify the noise coming from the receiver with an OpAmp?

Before you can do ANY noise measurements, you need to know the noise level internally generated by your receiving SYSTEM. Noise level will be measured in DB above what your receiver level is.

Paul

Can I use an inexpensive 433MHz receiver (pic) to evaluate the noise level in my local area?

No, but they can detect nearby transmitters.

Those receivers don't measure radio frequency emissions linearly, and the one you linked is superregenerative, which is one of the noisiest types of receiver known.

Transmission frequencies are subject to regulations in your country.

How to properly measure the noise floor in the 433MHz band?

Apparently, if TTN decided to avoid 433 due to constant violations there must be not enough stress on enforcing regulations.

To discover what works best for you, try both options and use the better one.

Professional test equipment is very expensive.

SeaWalker:
How to properly measure the noise floor in the 433MHz band?

With a spectrum analyzer.

SeaWalker:
I'd like to learn more about LoRa so I decided to build a few nodes but I'm unsure whether to use 433 or 868 MHz. TTN uses 868 MHz due to the excessive man-made noise in the 433MHz band due to alarms, cars, weather stations, etc.

Can I use an inexpensive 433MHz receiver (pic) to evaluate the noise level in my local area? If so, do I need to amplify the noise coming from the receiver with an OpAmp?

I believe you are confusing the concept of a noise floor and co-channel interference. The noise floor at UHF frequencies is largely driven by the receiver rather than environmental noise so there isn't much point in evaluating it with other than the objective receiver. Co-channel interference is real signals in the RF environment that are received in addition to the signal of interest. Since it is a function of the external environment any suitable receiver may be used to evaluate it.

LoRa is a spread spectrum signal, which is to say it has a much wider channel bandwidth than conventional receivers. Thus one would need a wide band and/or tuneable receiver to look at the LoRa signal channel. It's worth noting that spread spectrum radios are able to operate in the presence of significant levels of interference, which is their principle advantage over conventional radios.

At the hobbyist level a common approach is to use an RTL-SDR receiver with some control interface software such as GQRX or SDR-Sharp to look at the radio spectrum at the frequency of interest. This setup can be used effectively as a radio frequency spectrum analyzer. There have been projects using this sort of equipment to examine and decode the LoRa Waveform.

Also if this is just a learning exercise, you're getting a little sidetracked considering that Lora is intentionally designed to overcome interference. Why not just move on from this conundrum and set up some systems and see how they actually perform in your environment?