Best "box" to receive uncertified (SIL=0 or SIL=1) ADS-B IN data (NOT involving a tablet)?

SIL is not even processed by the receiver and is not part of the GDL90 interface. The GDL90 interface is raw data.and to make use of it you have to write a program to process the individual messages into something useful, such as traffic or FISB.

Garmin did the GDL90 under contract with the FAA to support testing of UAT based ADS-B in the Alaska Capstone project so they could test and validate the concept. The interface is public information and can be downloaded at https://www.faa.gov/nextgen/programs/adsb/Archival/media/GDL90_Public_ICD_RevA.PDF .
The interface of the actual GDL90 was RS422 at the physical level, but now others have used other physical layers such as BT or Wifi. The messages are the same. The original portable receivers were just UAT and later dual frequency receivers were made available. The Stratux device can receive 1090ES data and transform it into the GDL90 message structure, but whatever it attaches to has to process the messages.

The Pi’s serial port will be 0 – 3.3v: the RS232 standard is 12 volt signalling (although many devices will work with less – usually, most modern stuff is fine with 5v signalling). If you’re using the Pi for serial you’ll need to check the other device does 3.3v signalling (especially important if there is a data line from the device to the Pi – exceeding 3.3v on an input will damage the Pi’s GPIO). There are of course level shifter ICs (and probably one on a board you can just buy for the RPi)

The raspberry pi has a built in serial port in the GPIO pins, no need for conversion. You can probably do all you need on the pi with a slightly modified version of the dump1090 software.

Do you have a specification of the data you want on the serial port?

I got the Rosetta box last year to go with a tablet with EasyVFR for audio warnings and traffic displays plus the RS 232 converter wire to the Trig transponder for ADS-B out. The Rosetta has a few USB sockets under a cover, one has a GPS module plugged in that you can replace with a “certified” external antenna – which I did , just not a “certified” type – ahhmm , what is this exactly , the papers or the price that sets it apart from other top types available anywhere ? So not speaking about certified, what prevents you from setting non-SIL-0 on the transponder ? The Trig is the box to set SIL-1 or so – or so I guess ?? Can ATC see a difference in GPS performance at all ? We only had a few flights with the Rosetta so far and I get warnings on the Trig about position loss in periods but a few button presses clear this each time, no idea what might be the fault still. The internet flight following sites show our flights so the Trig seems to send ADS-B out but OGN Open Glider Network may do this job as well so I do not know which source is used. As RS232 is available from the Rosetta via USB converter cable my guess you could use this for other boxes to your liking.

Anyway the Pilotaware forum will be most useful for any mods around this topic.

Vic

Pilotaware will output GLD90 to RS232 using a USB to RS232 adaptor:

Exporting Data from PilotAware Units to Third Party Units
Introduction
PilotAware software can export location data from the on-board, non-certified GPS used on both PilotAware Classic and Rosetta units. For example, this can be used to provide some modern 1090MHz transponders, equipped with extended squitter, with the ability to provide ADSB-out when connected to a non-certified GPS input. †
† SIL level needs to be set to 0 (zero)
Physical Connection
An interconnecting lead that converts the USB output to an RS232 input is required between the two units. A suitable cable is available from Farnell here. Please note the cable must be an RS232 cable and not an RS232 TTL level cable.
The information available on the RS232 cable is provided on the Orange and Black leads
1. Orange Signal.
2. Black Ground.
This cable can be connected to any spare USB slot of the Rosetta or Classic unit, with the output of the chosen slot configured accordingly.
The numbering of the USB slots is as follows:
1. Top Left
2. Bottom Left
3. Top Right
4. Bottom Left
Configuring the Output
The configurations available on the ‘Configuration Page’ of the PilotAware Unit are as follows:
1. Auto
2. GPS
3. Transponder Trig
4. Transponder Funke
5. FLARM-out
6. FLARM-in
7. GDL90 (TBD)
8. MAVLINK (TBD)
9. LCD
In addition, the Baud rate can be changed to meet the individual connection requirement. 1. 4800
2. 9600
3. 19200 4. 38400 5. 57600 6. 115200

Transponder Manufacturers and Models
The physical input to, and the configuration of the host transponder will differ between manufacturers. This information will be obtained by consulting the manufacturers installation instructions and operating instructions. On some early model transponders’, a software update may be required. Also, not all models will have the required ‘extended squitter’ functionality. Please consult the manufacturer for model specific information.
Customers of PilotAware have connected to several types of modern transponder such as Trig, Becker and Funke who all provide input information in their manuals. Garmin is unfortunately reluctant to provide the information.
Help and Tips from the Forum
Experience and tips on how individual installations were done are provided by supporters on the PilotAware forum here . For information search on installing your type of transponder. Also provide information on your installation to help others.
For example, here is a thread on installing a GPS feed to a Becker Transponder and the help provided from the forum supporters.
Connecting More than One Device
More than one output can be provided from PilotAware Rosetta. For example, a GPS output for the transponder can be provided and also an output, on a second USB slot can be provided to show traffic on a glass screen such as a Dynon Skyview. Each port will be individually configured.
PilotAware Team.

The Air Avionics TRX1500A will receive ADS-B including SIL-0 and also Flarm and output on ARINC429 to a GTN etc
https://www.air-avionics.com/?wpdmpro=trx-1500-trx-1500a-manual

(and the PilotAware uses the GDL90 protocol, so another option is to turn GDL90 into whatever you need).