Note 5 - Fair Value Measurements - Fair Value by Categories of Long-lived Assets (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Intangible assets, impairment loss		$ (11,133)
Goodwill, impairment loss	0
Intangible Assets from Genasys Acquisition [Member]
Intangible assets, impairment loss		0
Patents [Member]
Intangible assets, impairment loss	0	(11,133)
Fair Value, Nonrecurring [Member]
Intangible assets, impairment loss	0
Goodwill, impairment loss			[1]
Fair Value, Nonrecurring [Member] | Intangible Assets from Genasys Acquisition [Member]
Intangible assets, impairment loss			[2]
Fair Value, Nonrecurring [Member] | Patents [Member]
Intangible assets, impairment loss		(11,133)	[3]
Reported Value Measurement [Member] | Fair Value, Nonrecurring [Member]
Goodwill, fair value	2,305,750	2,445,990	[1]
Reported Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Intangible Assets from Genasys Acquisition [Member]
Intangible assets, fair value	1,142,814	1,520,006	[2]
Reported Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Patents [Member]
Intangible assets, fair value	32,820	37,340	[3]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Goodwill, fair value			[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Goodwill, fair value			[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Goodwill, fair value	2,305,750	2,445,990	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Intangible Assets from Genasys Acquisition [Member] | Fair Value, Inputs, Level 1 [Member]
Intangible assets, fair value			[2]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Intangible Assets from Genasys Acquisition [Member] | Fair Value, Inputs, Level 2 [Member]
Intangible assets, fair value			[2]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Intangible Assets from Genasys Acquisition [Member] | Fair Value, Inputs, Level 3 [Member]
Intangible assets, fair value	1,142,814	1,520,006	[2]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Patents [Member] | Fair Value, Inputs, Level 1 [Member]
Intangible assets, fair value			[3]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Patents [Member] | Fair Value, Inputs, Level 2 [Member]
Intangible assets, fair value			[3]
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member] | Patents [Member] | Fair Value, Inputs, Level 3 [Member]
Intangible assets, fair value	$ 32,820	$ 37,340	[3]

[1] Represents acquired goodwill from the acquisition of Genasys Spain. There was no impairment related to these assets. Refer to Note 8, Goodwill and Intangible Assets, for more information.

[2] Represents acquired intangible assets from the acquisition of Genasys Spain. There was no impairment related to these assets. Refer to Note 8, Goodwill and Intangible Assets, for more information.

[3] During the year ended September 30, 2018, the Company determined that certain patents were impaired. The impaired patents related to products no longer sold by the Company.