Your Rig with USB Audio I/F and Linux Sound System

Please also check my page Sprig IC-7410 Setup

user1@Asrock:~$ uname -a
Linux Asrock 4.13.0-37-generic #42-Ubuntu SMP Wed Mar 7 14:13:23 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
user1@Asrock:~$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=17.10
DISTRIB_CODENAME=artful
DISTRIB_DESCRIPTION="Ubuntu 17.10"
user1@Asrock:~$ ls -l /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Apr  3 08:36 /dev/ttyUSB0

user1@Asrock:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 9: HDMI 3 [HDMI 3]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 10: HDMI 4 [HDMI 4]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 0: ALC1150 Analog [ALC1150 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 1: ALC1150 Digital [ALC1150 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ aplay -L | grep -n USB
83:    USB Audio CODEC, USB Audio
86:    USB Audio CODEC, USB Audio
89:    USB Audio CODEC, USB Audio
92:    USB Audio CODEC, USB Audio
95:    USB Audio CODEC, USB Audio
98:    USB Audio CODEC, USB Audio
101:    USB Audio CODEC, USB Audio
104:    USB Audio CODEC, USB Audio
107:    USB Audio CODEC, USB Audio
110:    USB Audio CODEC, USB Audio
113:    USB Audio CODEC, USB Audio
116:    USB Audio CODEC, USB Audio
119:    USB Audio CODEC, USB Audio
user1@Asrock:~$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 0: ALC1150 Analog [ALC1150 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 2: ALC1150 Alt Analog [ALC1150 Alt Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

user1@Asrock:~$ arecord -L | grep -n USB
8:    USB Audio CODEC, USB Audio
11:    USB Audio CODEC, USB Audio
14:    USB Audio CODEC, USB Audio
17:    USB Audio CODEC, USB Audio
20:    USB Audio CODEC, USB Audio
23:    USB Audio CODEC, USB Audio
26:    USB Audio CODEC, USB Audio
29:    USB Audio CODEC, USB Audio
32:    USB Audio CODEC, USB Audio
35:    USB Audio CODEC, USB Audio
38:    USB Audio CODEC, USB Audio
41:    USB Audio CODEC, USB Audio
44:    USB Audio CODEC, USB Audio
user1@Asrock:~$ cat /proc/asound/card1/stream0
Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed : USB Audio

Playback:
  Status: Stop
  Interface 1
    Altset 1
    Format: S16_LE
    Channels: 2
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000
  Interface 1
    Altset 2
    Format: S16_LE
    Channels: 1
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000
  Interface 1
    Altset 3
    Format: S8
    Channels: 2
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000
  Interface 1
    Altset 4
    Format: S8
    Channels: 1
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000
  Interface 1
    Altset 5
    Format: U8
    Channels: 2
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000
  Interface 1
    Altset 6
    Format: U8
    Channels: 1
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000

Capture:
  Status: Running
    Interface = 2
    Altset = 1
    Packet Size = 196
    Momentary freq = 48000 Hz (0x30.0000)
  Interface 2
    Altset 1
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 48000
  Interface 2
    Altset 2
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 48000
  Interface 2
    Altset 3
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 44100
  Interface 2
    Altset 4
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 44100
  Interface 2
    Altset 5
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 32000
  Interface 2
    Altset 6
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 32000
  Interface 2
    Altset 7
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 22050
  Interface 2
    Altset 8
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 22050
  Interface 2
    Altset 9
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 16000
  Interface 2
    Altset 10
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 16000
  Interface 2
    Altset 11
    Format: S8
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 16000
  Interface 2
    Altset 12
    Format: S8
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 16000
  Interface 2
    Altset 13
    Format: S8
    Channels: 2
    Endpoint: 4 IN (ASYNC)
    Rates: 8000
  Interface 2
    Altset 14
    Format: S8
    Channels: 1
    Endpoint: 4 IN (ASYNC)
    Rates: 8000
  Interface 2
    Altset 15
    Format: S16_LE
    Channels: 2
    Endpoint: 4 IN (SYNC)
    Rates: 11025
  Interface 2
    Altset 16
    Format: S16_LE
    Channels: 1
    Endpoint: 4 IN (SYNC)
    Rates: 11025
  Interface 2
    Altset 17
    Format: S8
    Channels: 2
    Endpoint: 4 IN (SYNC)
    Rates: 11025
  Interface 2
    Altset 18
    Format: S8
    Channels: 1
    Endpoint: 4 IN (SYNC)
    Rates: 11025

user1@Asrock:~$ man pactl
NAME
       pactl - Control a running PulseAudio sound server

user1@Asrock:~$ pactl stat
Currently in use: 20 blocks containing 564.2 KiB bytes total.
Allocated during whole lifetime: 3521853 blocks containing 1.9 GiB bytes total.
Sample cache size: 361.5 KiB

user1@Asrock:~$ pactl info
Server String: /run/user/1000/pulse/native
Library Protocol Version: 32
Server Protocol Version: 32
Is Local: yes
Client Index: 277
Tile Size: 65472
User Name: user1
Host Name: Asrock
Server Name: pulseaudio
Server Version: 10.0
Default Sample Specification: s16le 2ch 44100Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.pci-0000_00_1b.0.analog-stereo
Default Source: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
Cookie: 812a:9d7a

user1@Asrock:~$ pactl list | grep -n USB
64:	Argument: device_id="1" name="usb-Burr-Brown_from_TI_USB_Audio_CODEC-00" card_name="alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00" namereg_fail=false tsched=yes fixed_latency_range=no ignore_dB=no deferred_volume=yes use_ucm=yes card_properties="module-udev-detect.discovered=1"
373:	Name: alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
383:	Monitor Source: alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo.monitor
392:		alsa.name = "USB Audio"
393:		alsa.id = "USB Audio"
398:		alsa.card_name = "USB Audio CODEC"
399:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
403:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
409:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
417:		alsa.mixer_name = "USB Mixer"
418:		alsa.components = "USB08bb:2901"
558:	Name: alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo.monitor
568:	Monitor of Sink: alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
575:		alsa.card_name = "USB Audio CODEC"
576:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
580:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
586:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
595:	Name: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
614:		alsa.name = "USB Audio"
615:		alsa.id = "USB Audio"
620:		alsa.card_name = "USB Audio CODEC"
621:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
625:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
631:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
639:		alsa.mixer_name = "USB Mixer"
640:		alsa.components = "USB08bb:2901"
966:	Name: alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00
971:		alsa.card_name = "USB Audio CODEC"
972:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
976:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
982:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"

user1@Asrock:~$ pactl list | cat -n
   593	Source #6
   594		State: RUNNING
   595		Name: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
   596		Description: PCM2901 Audio Codec Digital Stereo (IEC958)
   597		Driver: module-alsa-card.c
   598		Sample Specification: s16le 2ch 48000Hz
   599		Channel Map: front-left,front-right
   600		Owner Module: 7
   601		Mute: no
   602		Volume: front-left: 13489 /  21% / -41.19 dB,   front-right: 13489 /  21% / -41.19 dB
   603		        balance 0.00
   604		Base Volume: 65536 / 100% / 0.00 dB
   605		Monitor of Sink: n/a
   606		Latency: 0 usec, configured 25000 usec
   607		Flags: HARDWARE DECIBEL_VOLUME LATENCY 
   608		Properties:
   609			alsa.resolution_bits = "16"
   610			device.api = "alsa"
   611			device.class = "sound"
   612			alsa.class = "generic"
   613			alsa.subclass = "generic-mix"
   614			alsa.name = "USB Audio"
   615			alsa.id = "USB Audio"
   616			alsa.subdevice = "0"
   617			alsa.subdevice_name = "subdevice #0"
   618			alsa.device = "0"
   619			alsa.card = "1"
   620			alsa.card_name = "USB Audio CODEC"
   621			alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
   622			alsa.driver_name = "snd_usb_audio"
   623			device.bus_path = "pci-0000:00:14.0-usb-0:1.1:1.0"
   624			sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1.1/3-1.1:1.0/sound/card1"
   625			udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
   626			device.bus = "usb"
   627			device.vendor.id = "08bb"
   628			device.vendor.name = "Texas Instruments"
   629			device.product.id = "2901"
   630			device.product.name = "PCM2901 Audio Codec"
   631			device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
   632			device.string = "iec958:1"
   633			device.buffering.buffer_size = "352800"
   634			device.buffering.fragment_size = "176400"
   635			device.access_mode = "mmap+timer"
   636			device.profile.name = "iec958-stereo"
   637			device.profile.description = "Digital Stereo (IEC958)"
   638			device.description = "PCM2901 Audio Codec Digital Stereo (IEC958)"
   639			alsa.mixer_name = "USB Mixer"
   640			alsa.components = "USB08bb:2901"
   641			module-udev-detect.discovered = "1"
   642			device.icon_name = "audio-card-usb"
   643		Ports:
   644			iec958-stereo-input: Digital Input (S/PDIF) (priority: 0)
   645		Active Port: iec958-stereo-input
   646		Formats:
   647			pcm
user1@Asrock:~$ man pacmd
NAME
       pacmd - Reconfigure a PulseAudio sound server during runtime

user1@Asrock:~$ pacmd stat
Memory blocks currently allocated: 20, size: 571.9 KiB.
Memory blocks allocated during the whole lifetime: 4054051, size: 2.9 GiB.
Memory blocks imported from other processes: 17, size: 146.4 KiB.
Memory blocks exported to other processes: 0, size: 0 B.
Total sample cache size: 361.5 KiB.
Default sample spec: s16le 2ch 44100Hz
Default channel map: front-left,front-right
Default sink name: alsa_output.pci-0000_00_1b.0.analog-stereo
Default source name: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
Memory blocks of type POOL: 1 allocated/2544888 accumulated.
Memory blocks of type POOL_EXTERNAL: 1 allocated/1 accumulated.
Memory blocks of type APPENDED: 1 allocated/1 accumulated.
Memory blocks of type USER: 0 allocated/0 accumulated.
Memory blocks of type FIXED: 0 allocated/1434700 accumulated.
Memory blocks of type IMPORTED: 17 allocated/74462 accumulated.

user1@Asrock:~$ pacmd info
Memory blocks currently allocated: 20, size: 564.2 KiB.
Memory blocks allocated during the whole lifetime: 4056432, size: 3.0 GiB.
Memory blocks imported from other processes: 16, size: 137.8 KiB.
Memory blocks exported to other processes: 1, size: 962 B.
Total sample cache size: 361.5 KiB.
Default sample spec: s16le 2ch 44100Hz
Default channel map: front-left,front-right
Default sink name: alsa_output.pci-0000_00_1b.0.analog-stereo
Default source name: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
Memory blocks of type POOL: 2 allocated/2546337 accumulated.
Memory blocks of type POOL_EXTERNAL: 1 allocated/1 accumulated.
Memory blocks of type APPENDED: 1 allocated/1 accumulated.
Memory blocks of type USER: 0 allocated/0 accumulated.
Memory blocks of type FIXED: 0 allocated/1435529 accumulated.
Memory blocks of type IMPORTED: 16 allocated/74565 accumulated.
30 module(s) loaded.

user1@Asrock:~$ pacmd list | grep -n USB
9:Default source name: alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo
80:	argument: <device_id="1" name="usb-Burr-Brown_from_TI_USB_Audio_CODEC-00" card_name="alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00" namereg_fail=false tsched=yes fixed_latency_range=no ignore_dB=no deferred_volume=yes use_ucm=yes card_properties="module-udev-detect.discovered=1">
416:	name: <alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo>
437:	card: 1 <alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00>
445:		alsa.name = "USB Audio"
446:		alsa.id = "USB Audio"
451:		alsa.card_name = "USB Audio CODEC"
452:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
456:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
462:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
470:		alsa.mixer_name = "USB Mixer"
471:		alsa.components = "USB08bb:2901"
630:	name: <alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo.monitor>
650:	card: 1 <alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00>
656:		alsa.card_name = "USB Audio CODEC"
657:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
661:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
667:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
672:	name: <alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo>
691:	card: 1 <alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00>
699:		alsa.name = "USB Audio"
700:		alsa.id = "USB Audio"
705:		alsa.card_name = "USB Audio CODEC"
706:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
710:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
716:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
724:		alsa.mixer_name = "USB Mixer"
725:		alsa.components = "USB08bb:2901"
911:	name: <alsa_card.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00>
916:		alsa.card_name = "USB Audio CODEC"
917:		alsa.long_card_name = "Burr-Brown from TI USB Audio CODEC at usb-0000:00:14.0-1.1, full speed"
921:		udev.id = "usb-Burr-Brown_from_TI_USB_Audio_CODEC-00"
927:		device.serial = "Burr-Brown_from_TI_USB_Audio_CODEC"
951:		alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo/#3: PCM2901 Audio Codec Digital Stereo (IEC958)
953:		alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo.monitor/#5: Monitor of PCM2901 Audio Codec Digital Stereo (IEC958)
954:		alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo/#6: PCM2901 Audio Codec Digital Stereo (IEC958)
1071:	source: 6 <alsa_input.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00.iec958-stereo>

SMA Calibration Kit (3)

This is with the ATT section of 0.5dB.

I do not know why the phase rotates so much. The size of the PCB is only 10cm, and assuming the velocity factor of around 0.5, the phase difference at 30MHz shall be less than (10cm x 2) / (10m x 0.5) x 360 deg = 14.4 deg.