Hey, new to the forums so I apologize if I'm not following any proper protocols or such.
I'm a computer scientist and programming is non-concern to me, however my experience with electronics engineering and RF is very limited. I'd like to build a wearable device for my dog that can be triggered by an RF signal roughly 1/4 to 1/2 mile away (understanding weather and terrain can reduce this) to log data or snap a photo.
I'm not sure if there are specific RF transmitter / receiver components that anyone would recommend or if anyone has any good resources that I could use as a primer to understanding RF and what frequencies work best at different ranges, etc. Any information or input would be greatly appreciated.
Terrain, like hills, can reduce RF range to essentially zero. But for line of sight or modest obstructions like a few trees, there are many commercial or DIY TX/RX modules that work out of the box for distances of up to 1 km or so. Some behave just like serial links, so you use simple print() statements to send data. Look for "wireless serial RF modules".
The longest range modules are LoRa, which are low power modules that can be used over hundreds of km in ideal conditions. However, there aren't many commercial options as the technique is still rather new and gaining acceptance. Google "arduino lora" for tutorials and project pages.
The frequency of RF determines the qualities of what may inhibit it. For example, WiFi is blocked well by foliage, especially pine needles, whereas a VHF TV station is not. Very low frequencies bend around the curve of the earth, ie: short-wave. This is only a generalization of it.
zeratal:
I could use as a primer to understanding RF and what frequencies work best at different ranges, etc. Any information or input would be greatly appreciated.
In general the lower the frequency the better the range, there is a concept of the 'attenuation of free space' which rises with frequency.
Whats more important to consider is which frequncy bands you can legally use. For most projects of your type you will be restricted to the ISM (industrial, scientific and medical) frequency bands allocated for your part of the world, no license is normally needed to use these bands.
ISM band allocations used in various parts of the World are 434Mhz, 868Mhz, 915Mhz and 2.4Ghz. There will be power level and duty cycle limits (how often you can transmit).
The affects of Weather are almost insignificant for the normal ISM bands, although they do start to have an affect above 5Ghz.
mattlogue:
Very low frequencies bend around the curve of the earth, ie: short-wave. This is only a generalization of it.
Short wave does NOT "bend around the earth", it gets around thanks to reflections against atmospheric layers. As a rule of thumb the ground wave (direct from transmitter to receiver) is 1 km per 1m of wavelength. So a 1,000m (300 kHz) wave gets about 1,000 km without needing reflections.
434 MHz and the higher ISM rely on direct line of sight connections, with as a rule of thumb the higher the frequency the more effected they are by obstacles.