I'm looking for an interesting Christmas present for my sons Chop...
I'd love something that:
- is easy to use and can give an immediate reward out of the box - e.g. tuning into something they couldn't otherwise hear, transmitting to walkie-talkies, 'hearing' an SMS leave a mobile phone
- allows room to grow, so that they can do more serious things with it if they're interested
- can be used from an Android phone or a Raspberry Pi (nice, but not essential)
I am only a relatively new user of the RSP/SDRUno combination, although I have used SDR receivers quite a bit, via a Raspberry Pi/USB dongle combo. So I will answer from a stand-point of RPi Vs. RSP Vs. ease of operation.
First up, SDR is a whole new world. It is not like your generic transistor radio or basic short-wave receiver. It does require a bit more of a learning curve to drive and obtain the best results from. But don't let this put you off getting one!
► Raspberry Pi (RPi) -
If your predominant concern is cost related, then obviously without argument the RPi setup is the way to go - with some caveats! The Raspberry Pi (regardless of version) need to have an OS installed on them (Rasbian - linux variant), which is not that hard, but you will need to edit some configuration files and make some to get the USB dongle to perform correctly. After all you are buying a $10 USB DVB-T television receiver dongle, so you have to do some config to stop it being a TV receiver - again not a complex task, but probably a bit daunting to someone that has never used linux or done anything in-depth computer wise.
Performance - Well it will depend on the USB dongle, for the record I have no tried the SDR-RTL dongles you see on eBay a lot these days, all mine (I have two) are just generic DVB-T RTL-2382U dongles. They cover from around 24 MHz through to around 1700 MHz. Mine are the "Rafael Micro R820T"
USB dongles, these have better frequency range then most. No matter what receiver you have, if you run a crap antenna - expect crap performance (reception). Having said that, on mine I used a very basic and easy to make end-fed coaxial dipole tuned for around 145 MHz with good results, for what it is the antenna performs very well. The Raspberry Pi and the USB dongle combo is quite a sensitive receiver, much better than very expensive scanners I have had.
I have tried the config mods to (supposedly) get the dongle to receive below 24 MHz, while you will see many a website with people saying how great they are receiving shortwave stations with it, in my experience it was pretty dismal. Actually it was so bad I could hardly hear the local AM broadcast station - and their transmitter is not even a kilometer from my house! I have never had any success at getting it to work under 24 MHz. Actually once you go below 30-35 MHz the performance drops off very rapidly in my experience.
► SDRPlay RSP
I cannot comment on the RSP1A, I have only used and owned the RSP2. I might push things here a bit and urge you to consider the RSP2. Yes it will cost a little more, but it will be money well spent, I can assure you! For a start you are not limited to just antenna input (socket). The RSP2 has three antenna inputs, they being HiZ, and two SMA inputs.
The HiZ (High Impedance - Balanced) is only usable between 1 Khz and 30 MHz, after clocking over to 30.0001 it will automatically switch to AntA (SMA connector) from memory. Although you can use both AntA and AntB for below 30 MHz.
Without going into technical boredom, my experiences with the RSP2 have been nothing short of impressive. The only exception to this would be on the low-wave band, 100 KHz to 500 KHz - I have not had much success there and get a lot of images from MW broadcast stations and not much else. Maybe someone can chip in here with their experiences on long-wave, and maybe what settings they used.
Long-wave aside, the RSP performs exceptionally well on MW (AM Broadcast band) and right across the HF spectrum. I can't offer any conclusions on 30 - 50 MHz, as here is Australia there is very little in the way of transmissions in that range, especially in my area. On the FM broadcast band, man it sizzles!!! It performs exceptionally on the FM broadcast band, as it does on all VHF bands I have used it on, which include the aviation band, amateur, marine and commercial VHF (160-180 MHz). UHF, well due to my rural location I have not as yet had much opportunity to test this end of the spectrum out. I will put a bit more effort into listening to the UHF segment over the next few days, and if you are interested can provide an update.My thoughts on what you should go with:
Without doubt I wholly recommend that you spend the extra coin and get the RSP2 and use the SDRUno software. You will be glad you did. The extra investment will provide you with good 'future proofing' and ensure that as their interests grow and expand, the RSP2 will be able to fully satisfy their growing interests.
Gawd I sound like I am writing an advert for the RSP2!
I assure you, other than being a very happy RSP2 owner/user I have no other connection to SDRPlay.To answer/comment on some of your other questions -
► Immediate reward out of the box:
Well I guess it is a matter of what you, or they rather, consider as reward. Do they love to solve and work things out? If so, then they are going to simply love SDR!! SDR, regardless of receiver or software isn't exactly a turn it on and turn the dial 'hey pa look what I'm hearing' scenario. It takes some learning and a lot of tinkering with settings to get the best possible performance from the receiver. In saying this you do not need a PhD in radio or software engineering to use an SDR receiver. It just takes some time and learning.
They are probably at an advantage in a lot of way. From what you have said, it appears they have not used radios or been around radios before-hand. They are not going to be trying to operate the receiver in a 'pre-SDR' manner.
► Hearing an SMS leave a mobile phone:
Well, in short that ain't going to happen! At least I am pretty sure of it
I am not sure what country you are in, but in most countries it is illegal to monitor telephone service communications. I don't think there is any countries still using analogue mobile phone services, again without getting to technical you may be able to receive the 'signal' but you will not be able to listen to it as you would an analogue transmission - it will be digital.
► Allows room to grow:
Think I covered this pretty well with my spiel about the RSP 2
So the answer (in the case of the RSP2) would be a definite YES!
I don't (in my opinion) believe the RSP1 is a 'long-term' proposition and if they become interested enough they may very quickly outgrow the RSP1 and you will find yourself forking out for a RSP2 (or whatever the current version is then) - get it now and save yourself the grief.
In respect to the android phone bit, not my area of expertise, someone else may care to enlighten you on this aspect. But I could not think of anything worse then having a phone (or even a tablet) as the interface to the radio.
Using it from a Raspberry Pi, yes there is an image for the Pi on the SDRPlay website that you can download. I don't believe there is a linux version of SDRUno, so whichever software you go with in respect to using a Raspberry Pi you are not going to get the same feature set as you do with SDRUno on a Windows machine. It is really a nice piece of software.
Think I have covered most of your concerns pretty well, if you have any further questions don't hesitate to ask, that is what the forum is for!