Low SNIR on custom carrier board

1

I have a custom carrier board I made for the notecard. All seems to work well however the SINR is extremely low. Is there any other diagnostics I can check in the card to figure out what could be the problem? Below results on a WBAN with main and div antenna

{“req”:“card.wireless”,“crc”:“0003:3ce09784”}
{‘crc’: ‘0003:68F3A61F’,
‘net’: {‘rsrq’: -9, ‘modem’: ‘EG91NAXDGAR07A01M1G_20.004.20.004’,
‘internal’: True, ‘band’: ‘LTE BAND 2’, ‘imsi’: ‘310170402126508’,
‘lac’: 2437,
‘sinr’: 17,
‘rssir’: -63,
‘bars’: 3,
‘mnc’: 410,
‘cid’: 29905586,
‘rssi’: -64,
‘mcc’: 310,
‘updated’: 1742906693,
‘rat’: ‘lte’,
‘iccid’: ‘89011704274021265088’,
‘imei’: ‘868032061254805’, ‘rsrp’: -89},
‘mode’: ‘auto’, ‘count’: 3, ‘status’: ‘{modem-off}’}

2

Hi @bkauf,

A low SINR value (but high RSSI and RSRP…and high bars) basically means you have a strong signal that’s just not very clean. It could mean external RF noise/interference. Are you using an external (flexible) antenna or an onboard antenna on your PCB?

Rob

3

Hi Rob, thank you for the quick response. This is an external flexible MOLEX 2125700100 antenna https://www.digikey.com/en/products/detail/molex/2125700100/10489644

4

Hi @bkauf,

That antenna should be fine. You could try experimenting with other flexible antennas with a more broad frequency range to see if there is any difference (e.g. the one we sell has proven quite reliable).

Rob

5

Thank you - I will test and let you know